I think if Bandai or whoever owns the DBZ franchise desire to buy it from the team, then and only then can they sell the game. As for additional content; the answer is no. I'm not one to speak for others (besides right now lol) but I'm pretty sure that the team have stated before that there will be no new characters or anything of that nature after the game is released. They simply want to finish it, and be done with it. It's called Final for one reason, and one reason only... this is the end, my oldest friend; the end /queue sad music.
edit: truth be told I didn't read everything you wrote. I don't think that colour change is entirely out of the realm of possibilities, but I also know that on an extensive list of things the team want to put into the game; changing the colour of your clothing would be at the very bottom. Do no fret, though, my young sir! If the past has taught us anything, it's that people love to tinker with the games that they love ~ And ESF:F will be a game that people love. What am I getting at here? People outside of the team have made hundreds of unique models for 1.2.3, and I'm positive people will do the same for Final. It will just take some time, that's all. If you don't want to wait for this then I implore you read up a few guides, and start modeling for yourself ~ It really is quite simple to do after you get the hang of it