Please be sure and tell the cashier's what you are paying. Yes, unless you live in the Stephenson Towers, which are designated as alcohol-prohibited residence halls. Yes, although this varies widely by hall based on the original design of the hall. You may find it best not to assume you can store much of anything besides a few boxes over the summer. Each hall has a FAQ that answers this question more specifically for that hall.
Access is paid for via room and board fees.
After that, if you have met the minimum requirements all you have to do is turn your computer on and open up a web browser, go through self-certification and reboot.