Free-roaming rabbits still need some type of cage or hutch. My rabbit likes his cage a lot, and stays in there quite a bit. He doesn't have a litter box, but he only goes in his cage. He only goes in the corner of that cage!!
Rabbits need to be chewing all the time. Their teeth grow non-stop, so chewing helps keep them from growing too long. If their teeth get too long, they can't eat
So, you need to provide some toys just for the rabbit to chew on. Mine has a branch, a basket (that I keep filled with crumbled newspaper, since he likes to dig, also) and some bird toys that are wooden. They also need other toys. Balls are fun, especially those ones that jingle when you roll them.
Rabbits are pretty smart, but you need to keep a close eye until they know what they can and cannot do. I start out by only allowing a small space, and staying with them. Then, slowly allow them more and more roaming freedom. I've found that if they start chewing on something they aren't supposed to, I just tap their nose (a touch, really!) or their hind end. VERY gently, just kind of to get their attention. They are pretty sensitive to scent, so if you find they are chewing carpet in a certain area, or are chewing on something in particular, spraying with something that smells strongly, like perfume, etc, can help.
Oh, and rabbits can be a little mischievous sometimes (think Peter Rabbit), so don't be surprised if you have to help fish the rabbit out from behind the entertainment center or something...
ETA: if they pee on the carpet, clean it with vinegar. Rabbits will keep going in the same spot if you use ammonia.