You really need to research each college you are interested in specifically as to their financial aid policy. There are 2 components:
- Is the school need blind or need aware for international students? There are very few schools that are need blind for internationals. Need blind means they will consider your application without regard to your ability to pay. Need aware means that it could be a factor.
- Does the school meet full need for admitted internationals? This means if you are accepted, the school will meet 100% of need as they calculate. There are very very few schools that are both need blind and 100% need met for internationals.
If you graduate with an Astrophysics major, it just means you have either a BA or a BS. There is no special certification/license. People pursuing a career in Astrophysics most likely go on to complete a PhD.
The cost for an MD in the US is as much if not greater than for an undergrad degree.
Finally, I would add that if you are set on US schools, you might want to include some less selective schools than those on your list. For the least competitive school on your list, Colgate, a 1340 puts you at the 25th percentile. Competition at selective schools is even greater for internationals than US students.