medicareeligibility and state medicaid rules for parents

[parentsponsor]

After I got my citizenship, I sponsored my parents for a Green Card.

Now I am finding it hard to buy insurance for them.

After 5 years of having the Green Card, and their turning 65, I understand they can get to buy-in into medicare.

Question 1) Is this 5 years from the date of AOS application or from issue of GC?

ALso many states do not employ the same criteria for medicaid. Question 2) What information is there about different state rules for immigrants?

Many people might have gone through these issues already. Perhaps you can share your solutions ...

Thanks in advance ...