Just make sure the driftwood is clean. You can scrub it good with bleach, rinse it very well, then let it sit in the sun for a day. The sun helps the chlorine to dissipate. And cypress mulch is fine.
When I clean I use a 10% bleach solution and then use the peroxide. Basically it will kill everything and the oxygen removes the clorine. I really hate mold.
My guys are in for the winter and I house them in large ponds. They have their own room, since our kids are all grown up.
During the summer they are outside in a homemade hutch.
I'll try to get some pics up.