I have 3 SVs from 3 different breeders. Each one scrutinized me thoroughly before letting me have a kitten. I filled out lengthy questionnaires, had to provide references, and I met each breeder. One is a few hours north of me so I got to spend quite a bit of time with her, getting to know each other and her cats. The other 2 are in So. Cal and insisted I pick up the kittens in person. I have no doubt that I would have come home empty handed had they sensed or had they seen something about me they didn't like.
We communicated several times by phone because they wanted to get a "feel" for me as a person and I was happy to oblige. We did have to make arrangements well in advance for the phone calls. Hobby breeders often have paying jobs & families on top of taking care of their cattery. Emails were always answered, sometimes quite late at night. And, yep, I too had to ask several questions repeatedly before I got answers. I understood that completely after I visited the cattery north of me. Aiyeeee, what a load of work caring for the cats & kittens and having to answer multiple inquiries from potential buyers -- enough to drive anyone bonkers. You'll understand the bonkers thing once your kitten arrives. If one can make you crazy, imagine 10 or more. LOL.
Make sure you are completely comfortable with the breeder and that s/he will be responsive to your questions after you receive the kitten. Yes, the kitten should have the 2nd series of vaccinations prior to shipping. I believe it's a requirement for the health certificate necessary to ship but it's also necessary for the health of the kitten.