How Does a Church Determine Who Gets Paid and Who's a Volunteer?

I'm curious what others do as far as letting people accept, or encouraging, gratuities, and also what types of workers in the church are paid and what is done on a volunteer basis. To me, when someone starts doing something on a very regular schedule, I think it's best to give them some kind of pay. An example I've seen is a person who volunteered to work with our audio-visual equipment. He came early every week to set up the microphones, computers for Power Point and sound recording, if equipment needed repair or replacement, he'd take care of it, and so on. After he did that for quite some time as a volunteer, we decided to pay him a certain amount per month (we asked if he'd be willing to accept it, of course).

So I'm not thinking we would pay the people who take their turn in the nursery, or take their turn bringing cookies, or that kind of thing, but when the tasks become more like an actual job, I think it's good to pay the person. Sometimes it's more gray. For example, there might be a piano player who plays nearly every week but not if she goes out of town. Should she be paid? And what about the person who fills in for her when she's out? And what about other instrumentalists who play every week unless they're out? The drummer, for example? Then there's the matter of gratuities. On occasion our church rents out the facilities for events such as weddings or funerals. If the family needs it, one of our members will run the sound booth for them. Sometimes the family gives that person a gratuity.

Should that be encouraged? Would it be better to set a fee and include it in the rental agreement? What do you all do?