So, I could get a game development team on Gamedev, make the game, and play it without having any lawsuits? Now, is there a way I could play with my friends over the internet after the game is all made and not be illegal?

Yes, I suppose that if JK Rowling agrees, and you change a few names, it won''t be illegal.

Also, I might be able to help with some of the stuff (though I still have my own game projects to worry about). And you may get responses from others, especially if you post what the game will be like (tile-based, characters, etc.)