I'm not really sure what you're trying to get at, but I'm going to assume that you're wondering if you'll simply be able to afford school. Here are my $0.02.
You will be able to get what your chosen school deems necessary. You can usually find a budget (includes tuition / living / misc costs) at each school's website. You may take out Stafford loans up until about $38K (somebody correct me, I haven't looked at this in a while) and then you can take as much GradPlus as you need to make up the rest. It is totally hassle-free. Your school's financial aid dept. will coordinate a lot of it, but basically, you figure out how much you want. Then, it's yours. Done. You reapply every year for more loan money.
Now, there are some things you should be aware of. There are two different Stafford loans that are included in the initial $38K figure I stated. So, with the GradPlus loan, you have 3 loans that you potentially will be taking out at once. They all have different interest rates and methods of capitalizing (adding interest into the loan amount so that you have to pay interest on interest.. for example: I take out $100 in loans. Interest is 10%/year. By the end of the year, I have $100 in loans plus $10 to pay back. If the loan capitalizes yearly, then in year two (if I don't take out any more loans), I'll have to pay $100 + $10 + (110 * 0.1). I think.
So, your loans as an OMS1 will gain more interest than your loans taken out as an OMS4. You can really minimize your final debt load by taking out less as an OMS1. Unfortunately, you also need to buy a lot of stuff and have less options as an OMS1 (since you might not know anything... I had to do a lot of my housing preparations for school completely over the internet). Tricky, eh? I'd suggest trying to borrow money from your parents/relatives if possible to try and minimize what you need to borrow in the first year.
Finally, I'll suggest that you calculate how much you need each year, and then, calculate how much debt you'll be in and how long it could take you to pay it off. It's just nice to be informed about what you're getting into since by the end of residency, the amount of money you'll owe might be enough for you to buy your parents' house. If you're from a rural area like mine, it'll be enough for you to buy your parents' house and your neighbor's house as well. Do your research. Being informed will keep you safe.
(and yes, there are loan forgiveness programs and such out there but I'm not going to cover them since I don't know much.)