Regarding the first question, what kind of specs do you have? You'll need a pretty swift machine with a high-speed connection to host games. If it's just the two of you, you should be ok.
As for IPs of multiplayer servers, try the in-game server browser or download the All Seeing Eye (search google for it).
If your friend wants to join a game on your computer he will need your computer's ip address. To get it on windows 95, 98, or ME, press the start buttoin, click on run, then type in "command"and hit enter. Then type "win ip config" (not sure about the spaces on this one, experiment) to get your ip address. On windows NT, 2000, or XP, press start, click run, then type "cmd" and press enter. Then type "ip config" to get your ip address