Tips for working in a pub for the first time?

I have a trial shift at my local pub at uni tomorrow. It's not a university bar, just one in the local village. It seems that the job is basically mine as long as I show I'm keen to learn (which I am) and I can handle the busy times (they're training me during the Friday night shift to show me what it's like at its worst to see if I feel ok with it).

I've got experience in waitressing so the food side isn't an issue for me. What I'm wondering is how easy is it to learn the bar and what's it really like? I have two friends that also work in their local pubs and they enjoy it now that they're confident and have been working there for a few years.

It is a job that you tend to enjoy or do you hate it? How easy is it to deal with drunk/aggressive/underage people? Any tips to help me? How do you deal with studying alongside it?

Thanks all!