Welcome to the world of bunnies!

I think most people put multiple litter boxes around the area if the bun is free roam in the room so they can go do their business as and when, instead of scrambling back to their cage if they are 10 feet away and need to go pee. If the cage is just attached to a pen though, then I would just stick with one in the cage That said, a bunny will be quite hard to litter train if they are not neutered/spayed, though not impossible.

As for introducing him to a new area, some people limit the space initially because the bun feels intimidated to explore, but others do this because they want to establish an area that the bunny will view as his/her safe zone. Are you planning to let the bunny freely roam your room 24/7, or is he going to be put in the cage at night or when you’re out?

The amount of litter boxes needed is very bun depended. Mine will ignore any other litter box that is not the one huge one in their pen and will always return to there, others will pee/poop on your floor if there are too few litter boxes and he has to run too far to “go”.

A neat way for a good amount of exercise is having the pen permanently attached to the cage, or, if that is not an option, have the pen attached when you are not at home.

Bam has two litter boxes, but he’s free roam 24/7. He uses both boxes. He chose the spots for them himself. Bun likes to do that. They pee in a spot and the human had better place the box in that spot.

Wick has three boxes and he is also free-roam 24/7. One is in the bedroom and two are on opposite ends of the large kitchen/dining/living area. So the layout of space is important as well.

I do think it’s very bun-dependent. 

Thor is free range in two rooms (living room and kitchen), and we’ve gotten away with one litter box. She was initially restricted to just the kitchen, and learned to use her litter box reliably. Once we gave her access to the living room, she was good about always going back when she needed to go, so we never added a second.