So basically the issue is that you, as MOM, are unsatisfied with the music in your church. Praise team, choir, none of it is running as smoothly as you would like it to. Am I correct?
I'm guessing you're a small church? I go to a small church, and my grandpa is the pastor, and although I've never dealt with an exactly identical situation, I feel for you. It's hard when you have a vision that no one else seems to understand.
I think one of the first things you need to do, is just be up front with the people and tell them your expectations. You don't want to sound like a dictator, but at the same time, remember that there's nothing wrong with striving for excellence. And like you said, first impressions for new people that walk into your church are a big thing. (Like I said, I go to a small church myself. Trust me, I know this to be very true. Guests can easily be persuaded one way or another by "superficial" things like that.)
You had mentioned there are people you have/know that are willing to use their gifts and would be able to make practices...is your issue that you don't want to hurt the feelings of your current musicians/singers by giving them the boot?