1. Course not, I know plenty of people around that age staying in halls. Definitely do it as it's the best way to make the most of university.
2. Look on the SAAS website and there should be some information. If you are from Scotland and go to university in Scotland you will of course have your fees paid for you, and then it takes into account other factors like whatever job you may have etc for your student loan. The minimum is £970 or something but not sure what it goes up to, and not really sure what kind of bursaries are available.