LEXUS,
Welcome to the forums.
Everything you want to achieve can be with some flexibility on your part.
Though it is going to take some effort.
You can make characters, get them free if you can find some or purchase them.
You can select characters only in Multi Player games.
You can create buildings directly in the editor from materials you will get in the download and CD.
You can indeed have your music play in a game.
Hope that helps a little.
Good luck with your project. Let us know how you get on.
"I am and forever will be your friend"