Here's a cage calculator that you can use to see how many rats your cage can house:
http://www.rattycorner.com/odds/calc.shtml Here's another one that allows you to also include the shelf measurements:
http://www.ratzrus.co.uk/ratguides/rat-cage-calculator.phpAs for diet, the staple of what a rat eats should be lab block or HIGH QUALITY dog food. I also use Suebee's Mix, which BaconWaffles mentioned. They also need fresh fruits and veggies. Since it's easier to tell you what rats CAN'T eat than everything that they CAN eat, also be sure to check out the forbidden foods list. Most branches are safe as long as there have been no pesticides or anything else dangerous on them EVER.
I also don't have much of a choice on where to get rats where I live, and have had a lot of pet store boys. Just make sure you check them very well before you buy them. Listen for labored, raspy, wheezy, or clicky breathing. Look for excess discharge from the eyes/nose, and check all over their bodies for hair loss or scabbing, especially around the ears and chin. Also consider their living conditions, how much room/ventillation they have, and if their bedding is too messy.
Carefresh isn't my fave, but it's fine. To avoid getting mites with your bedding, freeze it before use. Check out the Home Squeek Home section f the forum for other bedding ideas. I also always advise newbies to read thru EVERY POST on atleast the first page of Rat Care Corner, Home Squeek Home, and Rat Tails and Mug Shots. You'll learn A LOT that way! There are lots of smart people on this site to help you out.
