We stayed there twice (soon to be 3 times) and liked the Vistana so much that we purchased a week re-sale on eBay. As others have said, you want to try and get into either the Cascades, Lakes or Fountains sections. We prefer to be a little further away from the pools as it is a little quieter. In general, you can make all sorts of requests about the room but whether you get everything you asked for will depend a lot on how crowded it is when you're there. Our first trip we stayed in the Courts and the second time we stayed in the Fountains. The Fountains unit was a LOT nicer than the Courts unit, but the Courts unit was a LOT nicer than a hotel room, so if you end up in one of the older sections, it really isn't the end of the world.
Epcot is the closest park and it can take as little as 10 minutes door to door. MGM is next closest and then MK & AK. I don't remember it taking more than 20 minutes maximum from the time we left our room to the time we were walking in the gates (MK a little longer b/c you have to take the monorail or ferry after you park).
I actually think the restaurants there are okay. Definitely not extraordinary, but the food is not bad and you can't beat them for convenience. A lot of times we would head back from the parks to give the kids an afternoon nap and one of us would get some sandwiches to bring back to the room.
If you can, ask for Diamond Lane check-in. This could save you some time if you will be arriving during a crowded time.
Decide before you go as to whether you want to go on a timeshare presentation - at check-in, they WILL ask you. The reward is normally a voucher ($50-75) that can be applied to park tickets as well as some hotel vouchers. If you decide to attend a presentation, they are pretty good about keeping to the 90 minutes they promise. If you decide not to attend a presentation, you may get a phone call at some point during your stay asking you if you're really sure you don't want to attend. I don't remember there being a tremendous amount of pressure applied at check-in or during this phone call. Just be prepared and know in advance what you want to do.