Welcome Campertom... water damage, unfortunatly, is a trailers worst enemy, and correcting it properly can be a problem. Once you get moisture in there, things tend to rot fairly quickly. In my opinion, if you're taking this on you may have a bit more work ahead of you than you anticipated. I think you'll want to get right in there to see not only where the moisture got in, but how far in it got...and then replace anything that looks like it got damp.
For the windows..I think you might be talking about the trim around the aluminum frame that covers the screws holding the window's in ... if that's the case it's just cosmetic, so long as the screws have been caulked.
Info on the equipment inside (WH/Stove etc) is best found by googling the manufacturer of each piece of equipment - and of course forums like this one, depending on what you want to know. Most of these things are pretty standard when it comes to operating them.
The TV antenna should work fine as is - you'll want to turn on the 'booster' to improve reception. By 2011 (I think) all OTA TV signals will be digital, so you'll need to make sure your TV will accept that kind of signal. Other than that it'll pick up whatever is out there, although there are some better antenna's on the market.
Best of luck - post some pictures as you personalize your new trailer!
3 kids and Buddy the Dog;)
2010 JayFeather 23K
05 GMC Envoy XL