Drinks are ok to hold, just do so at waist level so you don't look like you're shielding yourself. Most people hold them up higher. Drink at waist level signals that you're relaxed, confident, and not a puritan or opposed to fun.

Small amount of alcohol is helpful in that sort of situation, more is harmful. Better to go dry if you don't know your range well (or if you're attending functions frequently, don't want a bad habit to form) but a little inhibition-loosening is almost always a good thing. If you're slurring speech or dropping things you've gone too far.

Name remembering thing is huge. If you forget though, just own up. Most people are understanding, since they generally forget them too. Unless like I once did you find yourself on date 3 and still not knowing. In that case it's time for some snooping. Junk mail saved the day.