Yeah, I have no issues with the fact that it's a 20 year old vehicle and understand the requirements needed to keep it in good shape. I'm just concerned about initial issues and things to look for (that's why I asked this forum!) and that it doesn't fall apart on me when I start driving it around, which from what I've learned, wouldn't happen on a car with a tough reputation like this one...
You should no great concern on this point. The price is right and if repair costs will be factored into it, even cheaper is better.
The issues you have should all be solvable. Sitting is hard on vehicles, but if you take care of the leaks and stuff, should be OK in the long run. These are reliable vehicles once you get things back in order.
If you haven't check the PS fluid level yet, that may simply be low. Don't know for sure, as I've never run mine low.
Get some dry silicone spray lube and spray the window tracks to help the windows move faster. I presume the truck was running when you tried them, but if not, try it again that way and use the up and down to spread the silicone down the tracks. Should be a great improvement, if not, the track felts are replaceable.