Hi Marcy,Looks like it's been a while since anyone has posted here, so I wonder if anyone is still reading this board.
But here's my perspective on your questions.
I was asked to lead worship at my church after being there only about 6 weeks. (That's the advantage of a very small congregation; it doesn't take long to become known.) After only 2 weeks a woman approached me about playing keyboard with me. So I said yeah, we'll have to get together at my house and play and see how it goes.
Well in the week before she was to come over, I was chatting with another worship leader friend of mine at another church and mentioned I would be getting together with a potential keyboard player. She asked me if the woman was any good. I replied, "I sure hope so, because the Lord already told me 'YES'!"
See my point? We can use logic and procedures to try and figure out stuff like this, but really I think each decision like this has to go before the Lord, and His answers don't always make sense to us.
For one thing, He sometimes values what is good for an individual more than what is good for the crowd. Like the shepherd in the parable who left 99 sheep who were doing OK together to go rescue one that was in peril. Sometimes the good of the one outweighs the good of the many--Star Trek taught us that, when eveyrone sacrificed their careers to go save Mr. Spock.
(Sorry, I see spiritual truths portrayed in almost every movie I watch.)
It would be foolish to NOT keep raising up new worship team members so they too can reach the bar you've set, but the only way to do that is to put them in before they can reach it. I wonder if maybe this could also stretch you and your current team members to be able to "adjust" around a weaker or less experienced player/singer?
So the first answer is, ask the Lord. He knows what the congregation really needs, He knows what an individual really needs, and He knows what you really need. But don't expect it to make sense or follow a pattern. He might tell you yes for one person and no for the next, for reasons which you may not be able to discern.
Kitty