OK...here goes
The questions may be quick, but, the answers certainly aren't!
I don't know of any RV manufacturer nowadays that will provide schematics for the water or electrical systems. They have them, but, they are evidently "guides" or "suggested readings" for the assemblers. They have a fairly liberal interpretation of the blueprints, so, even if you got a set, the odds of them being accurate are slim to none.
Here is a "generic" diagram of an RV's water system. You may have an additional sink, you may have an extra gray tank, but, the gist is the same. Water comes in and water goes out.
Your water heater bypass system should fall into one of two categories; the three valve type or the diverter with one-way valve type. This is an example of the three valve type (the one I've found on most FunFinders):
Here is the diverter with one-way valve type:
The three valve style uses three open/close valves; one on the inlet to the water heater (cold water supply, located at the base of the water heater), one on the water heater outlet (hot water supply located at the top of the water heater) and one on the "bypass" pipe that connects the inlet and outlet pipes. In normal operation the inlet valve (the bottom one) has its handle aligned with the pipe (that means it is open), outlet pipe has its handle aligned with the pipe (again, that means open) and the short "bypass" pipe will have its handle perpendicular to the pipe indicating that it is closed (blocking flow up the pipe). This forces the water into the bottom of the tank (cold) where the heater will do its thing and then the hot water will flow out of the top to give you hot water. To bypass the water heater, you turn the inlet valve to closed (handle perpendicular to the pipe), open the short pipe (bypass pipe) by aligning the handle to the pipe and then close the hot water supply pipe's valve by turning it perpendicular to the pipe. You can see in the diagram how the water heater is now bypassed. The cold water tries to flow into the water heater, but, encounters the closed inlet valve. The only way open to it, now, is the short pipe going up, where it encounters the closed hot water supply valve which then forces the water into the hot water pipes, but, since it has now bypassed the water heater, you won't have any hot water!
To put the water heater back in service, simply reverse the handle orientation on the three valves.
The other system, the diverter and one way valve, does the same thing, but, instead of on/off valves, it uses a diverter to change the path of the cold water; either into the bottom of the water heater or up the bypass pipe. The one way valve on the hot water supply of the water heater will let water from inside the water heater out, but, won't let water come in from the other direction. It is simpler and cheaper for the manufacturers, but, the one way valve is a "weak link" in that type of system. Over time, leaking and complete failure are quite common.
Now for the winterizing kit. It used to be that all trailers came with them, most anyway, but, as a cost cutting process, manufacturers are shipping RVs without them. If you have one, you are all set. If you don't, get one. Even if you don't use antifreeze (we'll get to that), you'll be ahead by having the kit installed. Here's where the winterizing kit fits:
The winterizing kit consists of a diverter and a suction hose. To draw water from your fresh water tank, the diverter handle lines up with the hose from your tank. To make the pump draw from your antifreeze bottle, turn the diverter's handle to line up with the smaller suction hose. See how the handles indicate flow direction or flow/no flow conditions?
That is pretty much it for the water systems with the exception of the low point drains and the fresh water tank drain. You'll have to crawl under the trailer to find the fresh water tank drain...it will be under the fresh water tank and is a petcock type valve. The low point drains (again, it may be necessary to crawl under your trailer to see where they are) are
usually located (on FunFinders) in the vicinity of the water heater and they have little key ring type loops on them. Grab the ring and pull up to open the valve, push it back down to close it. You should have two; cold and hot water. Some trailers don't actually have a valve, but, just caps on the pipes as they hang out of the trailer. In that case, crawl under the trailer and unscrew the caps (water will come out!)
Now for the winterization.
Here's a step-by-step (I hope I got them all!):
Your fresh water tank has a drain valve in it...you'll need to crawl under the TT to see it, but, first you should open that and let your FW tank drain out onto the ground. There may be a little water left in it, but, the volume in that big tank, if frozen, won't do any damage. When the FW tank is drained, run the water pump for a bit with a faucet open...it will clear the pump lines of water and it won't be damaged if run dry for a bit.
Next, go to the water heater (relieve the pressure in the tank first by opening a hot water faucet or pulling the relief valve). Throw your water heater bypass valves to take the tank out of the system. Remove the anode rod and plug assembly and let the tank's water drain onto the ground. While it is draining, open both the cold and hot water low point drain valves up. Go inside and open all of the faucets and hold the toilet flush valve down...this allows most of the water in the system to drain out onto the ground through the low point drains (that's what they are there for). By now, the hot water tank is drained...you either leave the little bit of water in there, or, I flush clean the tank with my garden hose and special curved "flush wand" for water heaters (you can get one at any RV shop). You'd be amazed at the amount of "crud" that accumulates in the tank. When I'm done with that, I've got that trusty syringe (I've actually got a bunch of them for use in my shop) and vacuum line hose and I suck the remaining water out of the bottom of the water heater. While you are cleaning the water heater, the water has been draining out of the low point drains. When done with the water heater you re-install the drain plug / anode assembly and it is good to go (don’t leave it out over the winter). Then close the low point drains, close all the faucets and hook up the antifreeze to the winterizing kit suction hose and turn the diverter valve from pulling from the fresh water tank to pulling from your antifreeze supply. Go inside and starting with the faucet closest to the shore water hook up, open it up and let "run" for a minute or so until you get a good stream of antifreeze. Hint: Get a 2.5 gallon or 5 gallon container (gas, but, mark really well that it contains antifreeze!) and fill that with antifreeze…will save a lot of steps for when that first gallon jug goes dry). Hot and cold. Close those, go to next faucet and repeat. Do the toilet and leave some antifreeze in the bowl; you never want to have the bowl dry, if the seals dry out they can crack and then your toilet leaks. Then go outside and do the "optional" outside shower port.
Now for the “other way”.
I've been "airing" my system for years...no problems, but, you must be thorough in the process, but, then again, you have to be thorough with the pink stuff, too. You will need an air compressor with storage tanks (not one of those “air your tires” compact units). You will also need an adapter to hook your air hose to the city water connection port; get a “hands free” adapter. Costs a little more, but, it screws to the city water connection and attaches to your compressor hose with a quick connect. Most of the process is the same, but, I’ll repeat the steps just so they’ll be linear and complete for both methods.
Your fresh water tank has a drain valve in it...you'll need to crawl under the TT to see it, but, first you should open that and let your FW tank drain out onto the ground. There may be a little water left in it, but, the volume in that big tank, if frozen, won't do any damage. When the FW tank is drained, run the water pump for a bit with a faucet open...it will clear the pump lines of water and it won't be damaged if run dry for a bit.
Next, go to the water heater (relieve the pressure in the tank first by opening a hot water faucet or pulling the relief valve). Throw your water heater bypass valves to take the tank out of the system. Remove the anode rod and plug assembly and let the tank's water drain onto the ground. While it is draining, open both the cold and hot water low point drain valves up. Go inside and open all of the faucets and hold the toilet flush valve down...this allows most of the water in the system to drain out onto the ground through the low point drains (that's what they are there for). By now, the hot water tank is drained...you either leave the little bit of water in there, or, I flush clean the tank with my garden hose and special curved "flush wand" for water heaters (you can get one at any RV shop). You'd be amazed at the amount of "crud" that accumulates in the tank. When I'm done with that, I've got that trusty syringe (I've actually got a bunch of them for use in my shop) and vacuum line hose and I suck the remaining water out of the bottom of the water heater. While I'm cleaning the water heater, the water has been draining out of the low point drains. When done with the water heater, I install the drain plug / anode assembly and it is good to go. I then close the low point drains, close all the faucets and hook up my air compressor using the adapter (again available at most RV supply houses; get the "no hands" type, your air hose from your compressor can hook up to it with a quick connect). Set air compressor for 45-50 psi and turn on. Go inside and starting with the faucet closest to the the shore water hook up, open it up and let "run" for a minute or so. Hot and cold. Close those, go to next faucet and repeat. Do the toilet and then go outside and do the "optional" outside shower port. For added "safety" I do a quick once around again on the inside faucets. Then I open the low points and let them run for a couple of minutes. While the low points are blowing the last vestiges of water out, I go inside and put 1 cup of the pink stuff down each drain (for the P traps) and a cup in the toilet. Turn off the air compressor and put it away. Close the low point drains and I'm done.
Sounds, complicated, but, once you've got the routine, it can be done almost as quickly as using the pink stuff; you've got to cover the same ground to put the stuff in as I do blowing the water out. A gallon of the pink stuff lasts me about 3 or 4 years, no pink stuff left in any lines next spring.
That's the way I do it. There are many that fear that there may still be enough water left in the system to cause damage...I've not had that problem. There are many that believe and trust in the pink stuff...that's fine, too, as I never had a problem with it back when I did the "traditional" winterizing, but, I could taste it, no matter how many times I flushed the system for the first couple of trips. The only time I couldn't taste it was when I "overdosed" the system with chlorine trying to get the taste to go away. I must say, I don't like the taste of chlorine any more than I liked the taste of the pink stuff...
Remember to reverse everything when finished so that next spring you are ready to flush the pink stuff or, in the case of "airing" you are just ready to pack up and go.
Hope that pretty much covers it