Make sure all your electrical cords (and anything else you do not want chewed on) are out of the way! Rabbits love to chew! They will chew anything and everything, regardless of whether or not it is good for them. You will need to make sure that the room(s) you let your rabbit out into are bunny-proofed.
While you can litter box train your rabbits, be prepared for little droppings everywhere -- that's one way that they sort of mark their territory, it's virtually impossible to expect them to only poop in their box, though generally, they will use the box for major dumps. They like to use the same corner or area most of the time, so the easiest way to train them is to find out which corner he/she will go in, and put the litter box there.
You should consider keeping the rabbit in his/her cage when you are not around (ie. going to sleep, leaving the room), so as to ensure that no unexpected accidents or unauthorized chewing occur.