PET RATS ARE SOOOO COOL.
First of all get more than one, and get the same sex. Rats do not bite however don't get in the habit of sticking food through the cage, they will grab fingers. They need exercise for sure, you can put together a pen with objects to run through or rat proof a room, but supervise they get in small places. Didn't know about the bricks I used to cut their nails. The only thing that you need to know is that they pee on you when they are young and the males will pee on you as adults too, it's like a marking dog. But the male is very very friendly. Let me know what you get? My daughter and I have raised a few. Oh and try and find a breeder, the pet shop rats are feeder rats and not bred properly.