IMO:

1a. Seller doesn't have to pay for an inspection ever. They have to
fill out a disclosure form. They may disclose, not disclose, or say
they don't know. [I am in the midwest US.] You should definitely pay
for an inspection [this is a given] and tell the inspection service,
before you pay them that they must determine the compsition of the
shingles. Funny thing, I bought a house that has no ecident asbestos
EXCEPT it has a few hundred sq ft of 8"x8" tiles, the thin kind you
glue down, not the ceramic variety. 8x8's are made with...asbestos.
SO I got that goin for me. They come up easy though.

2. Yes. No idea on cost, if you're in a blue state (Massachusetts,
NY), say, 10 grand.

3. I wouldn't buy such a house. Even if it all looks solid, god only
knows what future legislation and lawsuits will bring. There must be
other houses ?