1. For the last 4 years, VGC has always been a 4 vs. 4 Doubles format. Most likely, it'll be the same this upcoming season. (We had team preview turned on for all our battles this year, which made it a bit different from previous years.)
2. It's possible, but we'll just have to wait and see. Right now, most people are practicing Doubles Cup (Which is just all Pokemon except Ubers such as Kyogre and Groudon). Rules might be announced September 1st or sometime during September this year.
3. It's possible to do well without flawless Pokemon in VGC. I know that R Inanimate used Pokemon that didn't have incredible IV's this year, but he still did very well. You wouldn't need perfect IV's, but most of the best players do RNG their Pokemon and it really does help, because there's nothing bad that comes out of it. A lot of Smogon members are actually very kind about giving their RNG'd Pokemon for VGCers for free when tournaments start up too.