I'm a sound guy. And I make it a point to educate singers about the acoustics of your projected voice.
It is pretty simple: Think of it as like a bubble that you are blowing out of your mouth. It starts at your lips then expands until it reaches a certain distance where it comes back together.
You want the microphone to be on the edge of that bubble.
You sing acapella already, so you need to just practice with the mic until it is just a part of you. Like the stage itself. When you are up front you ain't singing in the shower anymore.
Back to mics: Don't sing straight into it up close or it doesn't sound good. If it must be against your chin, point it up. Then as you move it away, follow the contour of the bubble. With just a little practice you will find the sweet spot. It really is shaped like an enlongated bubble.
Project all you want, and move the mic out away until you find the right distance to point it straight at you. you will have stage speakers (monitors) so you can hear the other instruments and yourself. Practice with them.
If you are using mic stands for the performance, then testing this in rehearsal is very valuable in determining how close to the mic you should be.
The guys at the controls can control a LOT about how you sound.
But they cannot remove distortion. That's up to you.
btw, learn to love your voice. Nurture it. It is a gift to be able to sing. Enjoy it and make it the best it can be.
Maybe go to Youtube and find some live performances (Idol is great) and watch how people do it.