Skipped ahead to post my own personal breeding advice from experience.
I bred FANCY rats. Tailless Pandas and Tailless Black Eyed Ivories (sold em up to $300 a pop)
They were cute lol
BEDDING: I used aspen as it does not affect the ratties which are prone to upper respirory infections. Hate to say but 8 out of 10 rats have it. You can quaratine the animals and carefully choose the breeders.
FOOD Its a personal preference. I really liked how my rats were healthy, long lived, good breeders, nearly odor free(thanks to their diet), clean coats that did not produce dander. It was nice. I had 40 and no one could even smell them! LOL
Here is a link to what I actually used many years ago (10 years ago)
The block diet made their poop STINK and they pooped ALOT ugh.
http://hubpages.com/hub/Homemade-Rat-Diets
BREEDING I waited until my females were close to a year old, (9 months at the youngest but they were big). Why? Bigger, healthier litters. Less strain on the girls. Just like any other animal out there. Let em be "kids" until theyre all grown up!
I had 4 males at the most and they lived together in a group. The girls lived together as well. When it was time to be bred, I put the girl(s) with the male of choice in a new cage for a day. Sometimes up to a week. Then I remove em. WHY?? The boys, just like any man out there. Constantly harass the girls into mating. The girls only need to be mated one time and mate her again once her litters weaned and shes recovered.
Again, bigger litters
You notice I keep saying bigger litters. Just how many did mine have. Well, they averaged anywhere from 18-24 pups per litter.
The time and effort put into them was well spent IMO
My rats were very friendly, they didnt attack when they became "culled" (fed off to a snake).
Do research on fancy rat keeping, just my personal preference.
Mine were pets and feeders and they made enough babies to the point where i sold the babies for a nice profit.
GOOD LUCK
PM if you got questions