After a good first date, a guy invited me over to his place for a movie marathon. I don't mind getting a little frisky (i. e making out, maybe going down on him) and he seems like a genuinely sweet guy, but if he invited me over, is he expecting we're gonna go all the way?
We can't tell you what he expects. However, like someone already suggested below, just be yourself and don't do anything you wouldn't be comfortable with doing; if anything sexual happens, it should be because you're both comfortable with it and that's what you want.
I don't know... maybe because I'm in my late 20's I feel this way, but it is my golden rule never to do a first date at someones home. That's something I do when I am better acquainted with the person. When I feel like things are moving towards that point, then I will visit his home if he offers. But there's nothing wrong with being wined and dined, and then doing it in return (if he doesn't mind). Going to someones home is a intimate and very private setting, anything can happen!