1. Tell your dad that it is more efficient/costs nothing compared to making a phone call. All of the instant messengers (except for Trillian Pro) are free. If he's letting you onto a forum, I don't see why he wouldn't let you tank on AIM.
2. It will work with every operating system you'd have unless it's a mac or linux machine.
3. Yes, it has ICQ.
ICQ=IRC=AIM=MSN=YAHOO=ALL CHAT CLIENTS
RedHat, I'm (hopefully) going to be building the computer that is in the link in my sig
Will run xp fine i think