I used to be a rat person.. for YEARS. They are still my favorite small animal.. I just can't keep them any more
The biggest rat forum I know of is (broken link removed) It's not anti-breeding though.. just to give you fair warning.
At one point I was a very frequent poster.. I haven't really been there in a few years now though.. because I haven't had rats in almost 4 years (I made the choice 6 years ago not to get any more due to escalating allergies.. it took a while until I didn't have any more though.. but the difference from just having one last rat, to not having any after he passed, was shocking.. I didn't realize how bad I really felt until I wasn't exposed to those allergens any more).
The "gold standard" for rat cages was Martin's Cages.. I don't know if it still is... I know there are other "suitable" options out there than there used to be, but as with pigs, bigger is better - you really can't go TOO big. My preferred cage is an R-695 (powdercoated) with a flip top (the flip top is handy more for cleaning than accessing rats - the doors are plenty big)... that gives you lots of room for "stuff" for them, and plenty of room for up to 6 girls or 4-5 boys. I wouldn't recommend anything smaller than an R-680 for two.
About 10 years ago "
GROTTO" style cages were popular.. they are basically converted cabinets or bookshelves, I suppose the rat equivalent of the C&C cage, but they're very high maintenance. Rats pee on everything (it's just what they do), and in a cage with solid shelving, you have to be diligent about keeping things clean (multiple times a day) or you increase their risk of bumblefoot (which they can also get on wire flooring, however with enough soft options like hammocks and baskets and such, the risk is low). Rats will chew up and eventually destroy almost everything you keep in their cage - so covering surfaces with fleece or other soft bedding usually doesn't do more but give your rats something to entertain themselves with, though some rats are the exception to that rule - don't expect yours will be, just be pleasantly surprised if they are.
Good luck, if you decide to adopt them.. they are truly charming, I'm sure it won't take you too long to fall for them