I've applied for 2 US student visas in the past, although one was for a study abroad year, so the process was slightly different than a proper application to the university.
do you have to be accepted into the college first?
Yes - you can't apply for the visa until you have specific visa paperwork from the university.
do you have to fly out to the college first and have an interview?
That's up to you. They may interview you over the phone or they may even pay for you to visit them.
oh and another thing would it be better to get my drivers license here first in the UK or wait til I move there.
If you get your licence before you go, you may be able to get a US licence automatically... or you may have to take US tests as well. From what I've heard the US test can be really easy though.
Do most colleges have on campus accommodation where you can stay?
Usually - like in the UK, they have halls of residence (dorms). They can be more expensive than living off-campus and are more restrictive... you may be required to pay for a specific meal plan and they may well be single-sex... girls only or boys only living on a floor, or single-sex apartments. It depends on the university though.
Be aware that US universities will have a much stricter view on alcohol than UK universities as the drinking age is 21. The university I attended was 'dry', meaning that alcohol was strictly illegal on campus. If you were caught with alcohol in your room, you were sent to Substance Abuse Counselling and AA meetings. This happened to a friend of mine... he was 24 and legally allowed to drink, but they found 1 bottle of beer in his room and he got disciplined for it!
I'll detail my application experience here:
October 2006: While doing my UK masters, I applied for a PhD at a US university. I had already attended a US university for a year in 2003/04 and one of my professors had said if I ever wanted to come back for 'grad school', to get in contact, so I did. I emailed her and asked about the possibility of me working with her for a PhD. We exchanged a couple of emails and then we had an informal phone interview. She said that normally the department would fly prospective students out to see the school and the department, but it wasn't necessary for me because I'd already spent a year studying there.
November and December 2006: I studied for the General GRE exam involving English and Maths tests and an essay paper... US graduate students have to take the GRE in order to apply.The undergraduate equivalent would be the SATs (which you've probably heard about on TV/in movies), which you may be required to take before you can apply.
January 2007: I travelled to London to take the GRE exam (it cost about £100 in total I think)
January 2007: I filled out the university application form, paid the fee to apply, gathered any other documents they needed and mailed it to the US university.
February 2007: I got an email saying I had been accepted to the university to start in Fall 2007 (August 2007) and was being awarded full funding and a $5,000 fellowship grant! I asked to defer my entry to Spring 2008 (January 2008) as I was going to be working on my masters thesis until September 2007.
September 2007: I received my I-20 form... which is a very important document for the visa (you can't travel in or out of the US without it while you have a student visa - if you leave the US for a trip, you must get it signed by the international office of the university)... it details your acceptance to the university, when you will start and finish, and any funding you have been awarded.
September 2007: I called the US Embassy in London to book a visa interview. You have to pay for the visa during this phone call (and it costs £1.23 per minute, for an 8-minute call).
November 2007: I attended my visa interview (involving up to 4 hours of sitting in the embassy being bored before having a 2-minute interview)... my visa was issued 2 weeks later
(I had a bit of a complicated situation as I was stopped by the police in August 2007 and was just over the alcohol limit...so I now have a drink-drive conviction. This meant having to wait 2 months for a special visa appointment for applicants with a criminal conviction and I had to pay £250 for a blood test before they would issue my visa. It also means I cannot travel to the US again without a visa, even as a tourist).
December 2007: I booked my flights to the US. Somewhere between September and December, I applied for a room in university accommodation (can't remember when though).
January 2008: I moved to the US on my student visa.