1. I think he'll always remain coach of the Lakers. I don't think you can change it, but in association mode, it can get to a point where he'll retire, and you'll be able to hire a new coach.
2. It's called Association in 2K, but I'd imagine it has the 25 years that Live also had, though it could be more.
3. Yes, you can. You can either stock it up on real players, or create your own players and put them on that team.
4. You can edit a player's ratings, tendencies, and even salary during the mode, but you can't create another player. There are draft classes which you can have the game generate, or you can download from 2K share. I'd recommend creating your player there, so he can be drafted during the offseason.
5. Not sure about this one. No, you can't edit their height and weight iirc, though.
6. Yes, you can edit Kwame Brown to be the next Hakeem Olajuwon if you wanted. That's how much freedom association gives you in 2K.
7. Do you mean in association mode? If it is, I don't think so, because the rookie faces are pretty generic (although you don't see many porno mustaches like in Live). But yeah, I'm not sure about this one either.
8. Yes, you can. Some of the offers are ridiculous, and some CPU trades are pretty ridiculous as well. I was once offered David West for Yao Ming and Aaron Brooks, or something along those lines. 2K even allows you to do trades for other teams.
9. Yes, you can switch teams in 2K. You go to General Manager > Resign Position, and then you can choose whatever team you want to go to. That's also how you do trades for other teams, by resigning position.
Hope I was of some help. Hopefully someone else can answer the questions I wasn't sure about.