there are a few ways to find a rescue of a specific breed. first, look for breed-specific local rescues, like this one i just found with a quick google: http://wecarerottweilerrescue.homestead.com/

or you could find a local shelter and see if they can put you on a call list for when a rottie does come in.

your best bet would be to go with a breed-specific rescue. often these dogs have been fostered in home environments, so they can tell you their quirks and things like, are they good with cats and/or other dogs.

and while it's always tempting to get a puppy, adult dogs are great because they've already settled into their adult temperaments- no teenage mood swings or personality changes to worry about, not to mention the slightly lower energy level, haha!

i'm a dog rescue master, lol, so feel free to ask many any questions you can think of!