First of all thanks for the replies. Yes,the project will surely be a not payed one,so the main reason for someone to join in is the opportunity to have somenthing for a portfolo. Making experience is useful to everyone,hardly someone will offer you a paid project without it.
@dakota The problem whith officially kicking out people is that they could get angry,even after a while and deny you the right to use their works. I was thinking more to a "leave them inactive and just replace them" thing. What do you think of it?
@Krohm The idea to keep costant contact with them (without beibg ossessive ) is a nice one.At least i'll have a stable feedback. Yes,i'm frequenting university,but I always put at least 3-4 hours into the project every evening. For the engine:I know it's a bit of work but I prefer to have all te programming part on me to avoid delays from others.
Anyway,just to have an idea,how many people should I look for in the beginning to make sprites etc.?
Ps:sorry for not quoting and for mistakes but i'm writing from a mobile.