Heh, I just got off work from my bar about an hour ago.
We use to have a strict hiring policy on age at my bar; here in Texas you just have to be 18 to serve alcohol; but since we opened up the Grill we have hired a couple of staff member that are under 21- one is a waitress and the other is a cook.
Also before the Grill was opened we were a 21 and up bar- meaning only those over 21 could get in. Now its like that only after 10, thats when I close the grill at night.
We have some goofy laws down here concerning alcohol.
A bar is not an easy place to work. Not for the waitstaff, the bartender, owner, or even the cooks. If its a heavy bar you will encounter a$$holes and drunks and a mix of those. It takes patience and skill to be able to handle these folks. Sad to say, when you are younger than they are (i.e. cant drink) it will be harder for them to take you serious, respect you, give you the time of day. You have to be able to spot who you can approach, who you should avoid, how to handle the many situations that can and will arise.
I have dealt with lots and lots of drunks (sometimes I too am a little drunk- not the best idea when performing

)
They can be your best viewer and your worst viewer. You really have to have great audience control. There are things that you have to learn about people when they get drunk. Their reaction time, attention span, sight, etc.
These are just a few things to take into account, before attempting this venue. I can go on, but I am tired. Maybe Paddy or the Caff can pick up, add in or differ on a point I made. They both have more experience than me, I am quite sure of that.
Also will go through lots of cards due to spillage or drinks, sticky hands, dropping the cards, and lets not forget my favorite vomiting.