Here's a friendly reminder that multiboxing with several accounts that are not registered in the same name. (Which I imagine is the case with you and your friends account.) Will almost surely result in a permanent ban sooner or later on some or all of the accounts. I strongly advise to make sure all accounts are in your name, and your name only.

Other then that, welcome! As for your questions, the answer is in the first reply, basicly. Stroll through the wiki, if you then stumble on specific problems, can always ask about those ofcourse. In any case, there isn't any "one single way" to multibox, and one of the most fun aspects of multiboxing is finding a process or system that works best for you.