Re: hooking up
That is NOT true. Hooking up doesn't necessarily have to be sex related.
ie. "We hooked up last night." can mean we went to see a movie or out for a drink. Of course, it can also mean sex but more often than not it can be used to describe two people getting together casually or it can describe two people starting a relationship ie. "They hooked up last year."
Another example, "X and Y hooked up last night after the party," can mean they got together, made out, had sex, whatever...
So as you can see, it can mean a variety of things, it just depends in what context it was used.