$100K sounds a bit on the low end to me. If your school’s tuition is $20K, you will need at least another $10-$15K or so per year for living expenses, food, transportation, books, etc. So that puts you more at $120-$140. Also realize that tuition goes up every year, sometimes by 15% or more. However, if your school offers grants or scholarships, you may be able to reduce your debt somewhat.
As for getting student loans, it’s very easy to get Stafford loans for up to $38,500 per year. If you need more than that, it gets a little trickier because you have to have good credit or a co-signer.