Most of the time the individual goes after the bar, not the bouncer if they want to file charges. However make sure you have in writing that the bar will pay your legal fees just incase you are charged with something as an idividual.
If it is more than just escorting a patron out and any physical altercation happens the cops should be called to cover your ***, but usually just the mention of cops sends the idiots running. I have never been charged personally, but the bar I work for has numerous assault charges against them and I was called as a defendant/witness a few times. The bar wins everytime, it is hard to defend your actions when you were drunk at the time.
I have never seriously hurt anyone on the job, but I did break a guys nose when he "accidently" slammed into the door frame while I was escorting him out the door. I am not a big fan of tough guys who harrass or beat women and he was really disrespectful to a few of our women bartenders. It takes a lot to get them pissed and they take a lot of abuse for the cash they get, but even they asked us to throw him out.
Recently a kid was celebrating his 21st and got a bit too drunk so we kicked him out. He came back and kicked the door, spiderwebbing the glass and ran. I chased him down and tackled him, we called the cops and he was arrested for drunk/disorderly. He ended up paying more than $2000 after fines and the cost to fix the door. Nice way to remember your very expensive 21st