You mean a government loan, or one from your bank? For the government one they check your income and what they can give is based on that. So if you make above a certain threshold (which is really not too high), you won't get one. Alternatively you can get a student line of credit from your bank, which doesn't have the interest free grace period, but they are your only option if you have a decent salary.
Yes they can if you don't make enough money to pay for it. A loan is something you pay back, so there is no restriction to get one once someone is a PR.