Yes, when I was MSTP, I qualified for about $15,000 in Stafford loans/year. Most of it was subsidized too. However, when I was MD-PhD, my salary was $15k/year. I hear that some programs are paying their MD-PhD candidates $24K/year now.
yes - because your cost of living will be calculated with the tuition cost included. even with your stipend you will still be eligible for stafford loans.
to be more precise - it depends on your schools cost of living budget. if you are attending an instate public school, you may not qualify for staffords