As for the rest of the stuff aside from drinking - don’t worry about it too much. First of all, you’ve got at least a year and a half until your first college party. It’s a little early to start worrying about what you would say or do.
Parties in college are held at all kinds of different venues. If the college you attend has Greek life, then fraternities do often throw parties. At many colleges, the fraternities have their own physical houses and so they throw parties in or near them. However, some colleges don’t have houses for all of their fraternities, and some fraternities may choose to throw some or all of their parties not in their house. So those parties may be held at event venues (on-campus or off). Some of them have suites on campus in the residence halls and they throw them there. Some of them have no alcohol at all - a fraternity on the campus I went to grad school on never offered any alcohol at their parties. When I went to go to the pre-check before their parties they were usually setting up live music. Sometimes they are closed (small, invite-only parties, occasionally done with the members of maybe one other sorority) and sometimes they are open (anyone…sort of…can go).
But there are soooooo many other kinds of parties other than fraternity parties. College students throw parties for all kinds of reasons, including no reason at all. They could be a small 8-person get together in someone’s suite/dorm room; a party that takes over an entire dorm; a blow-out off campus at a bar somewhere or anywhere in between. Some have alcohol and some don’t. Some are even college-sanctioned parties or college-sponsored. At my campus, lots of people moved off campus after their sophomore year and so they started to have house parties. There were also lots of parties at clubs since Atlanta has a big club culture. There are parties where the music is so loud you can’t even attempt to talk to anyone, and parties where they’re playing soft music and the point is to mix and mingle and chat.
Whatever you like, you can probably find a party to suit your personality.
You can talk to whoever you want. You should probably start by introducing yourself. College students have pretty standard introductory questions that make talking easy (What’s your major? What classes are you taking this semester? Where are you from? What dorm do you live in? How do you like Our College so far?) But just basically be a decent human being, as I am sure you are, and you should be fine 