First, Congrats! Ratties are tons of fun.
Second, I agree on getting your new guy a roommate. They are very social and need companionship. We rescued two brothers together.
Third, that cage is indeed very small. Our boys have a mansion, so they are spoiled, but they need room enough to run around, etc..
I pretty much agree with what Kay has said. Carefresh bedding, while expensive (At least in my area) is very much worth the cost as it lasts a lot longer.
You may also want to talk to Squidbert.. she's got the 411 on the ratties!