Rats wrastle like crazy, as long as they dont cut each other up I wouldnt worry. How old are these rats, is one male and female? If so the male is probably trying to get lucky, but if the female is determined enough she can refuse his advances for weeks until they get to be friends

Get some lab blocks, +becky's mix is a good idea. Im sure they can eat apples, and I don't see why they couldnt eat pineapples but Im not sure

I would say use low-dust pine. It helps mask the odor better IMO. Someone made a post about using stall dry, but barring that I would say use a small layer of baking soda. After much trial and error I've not been able to link the baking soda as a health hazard, and it helps a TON in absorbing and neutralizing urine.

Also, if you have to, just change everything twice a week. If you use pine/baking soda and change twice a week, I don't see how 2 rats would even come close to smelling.

Check out stickies in this section for Q and A, not sure about a caresheet.