Go to www.rabbit.org - that's the House Rabbit society's website, and it has lots of information to help you.

Rabbits are usually very easy to litterbox train, but it's not possible to keep them from chewing, so read the FAQ'a at that site on how to bunny-proof! They also have tips on how to introduce a bunny into a home that already has pets. If either of your dogs has a strong "prey drive" you aren't going to be able to leave them all alone together, someone will have to be caged for the bunny's safety.

Rabbits don't necessarily need a lot of room, just some space and lots of love!