Everybody's opinion on what is good role-playing varies. I wouldn't worry about whether or not you are and instead just have fun with it.
The forums ( www.seaofdragons.com/forum ) has information on the server. But were you asking about the server or the game itself? It'll be easier to give info if I know.
Yes, you do. However, the server is set up so that when you connect, all the files that you need will automatically download into the appropriate folders on your computer. All you need to get are the game and the two expansions. I know it's available on Steam as a package deal.
Around 5 PM to 11 PM CST (GMT -6). I'm the one who DMs most, but I haven't had a lot of chance to do much of it of late so my own times are sporadic.