you dont have to feed them in a different tank, i do but its not necessary. NEVER use any kind of sand or fine dirt with them though, aspen is safe to digest in small amounts, so unless the rat is totally covered, i wouldnt worry about it
mines in a 55 as well, and the lamp on the left is 100 and 75 on the right, 100 is too hot though, so i use foil to regulate it by blocking most of the beam, if you look, you k=can kinda see it in the photo, its a rectangle of light instead of circle