How to talk to breeders?

They are people like anybody else. Just be a judgement call how pro this may be. A private house setting you can be casual throughout. A commercial setting you can keep it professional but friendly.
A friend in Nevada has an exotic pet store and most of he animals they breed themselves, mostly snakes.
The staff are friendly and will show you their breeding facilities and more than happy to answer any questions.
Smart people with background in various animals, Ken is zoologist,40 years with snakes and exotics.
Where I got my last ratties. Talk regular people, even if it is a younger person breeding in a garage.
Helps when you can ask things like are the rats socialized at all at the time of weaning and perhaps see the place where they are bred and kept. Some red lights that say BYB are dirty, crowded cages breeding related parents and only concerned with the selling and money. Good breeders will usually quiz you about your experience with rats and have concern about the animals.
Like getting a dog or cat. When I got my lab, the people were nice enough to invite me for dinner so go figure.

They're breeders. They would appreciate it if you cut the foreplay and get down to business.

versify.