Yes, we're using a router.
you can use single player characters if you're playing closed battle net.
My friend did it, I just don't talk to him anymore so i have no way of asking, we made single player characters, and we leveled together in a TC/IP or whatever game.
I just would like to know if I create a game on my computer, how he can connect, we have the same IP's, I don't think it'll let us.