Nick should perhaps fight the toughest one in each of the cliques (Nerds excluded...they have no tough membes)....Damon, Derby, and whoever is left toughest in the Greasers....He has already had a go-around with Trent, and possibly have a go-around with Wade and Davis, since they're too stupid to leave him alone.
Jimmy is to be a shadow, only coming out in the open at night. Only Tony & Constantinos even knows he has escaped (besides the Cops and the Haringtons), and it should stay that way.
Envision Nick as an enforcer for Tony (not that he couldn't take care of himself), as a force for reluctant good against the forces of evil at Bullworth. And as to a friend, Nick already has his first friend....Tony.