Medical coverage for greencard (Seniors)

[srinic]

We are planning to apply for greencard for my Father-in-law (68 yrs) and Mother-in-law (65 yrs). One of our main concern has been how to give them medical coverage.

I am really looking forward for some answers for the following:

1. Once they get their greencard will they be covered by Medicare?

2. Will they get medical coverage after they get their citizenship?

2. I am in Texas and my BIL is in California. Does this have any implications? I have heard that in California that permanent residents get insurance.

3. If they cannot get and we have to buy private insurance, how much would approx expenses?
Which are the insurance companies offering them?

Thanks in advance