Rats do need a house, in case it is cold at night, they need somewhere where they can huddle and their heat not be lost as easily.
don't get them hamster/gerbil etc houses/toys as they are far too small and they won't fit when adults. Ferplast and a few others make rat houses, but you can also use rabbit and ferret furniture and toys.
as for bedding we use the pre-shredded tissue paper from pets at home at the moment, it's expensive but very good, keeps smells at bay, there are also cardboard versions (any bedding must be 'dust free' to stop resp and eye problems). if in doubt check the link below for what you can and can't use:
Safe And Healthy Bedding For Rodents :: Rat Rescue
we just cover the floor with the tissue and let the rats sort out their house etc themselves, they like doing that.
They will nibble everything so expect any existing holes in house you buy to get bigger as new doors will be made.
This lady is also very knowledgable and should give you lots of good info on any problems you might encounter, and we're always here to help
Good luck with your furries, can't wait to see the pics.
Critter City - By Sandra Todd of Allexperts.com