tomic601,
You probably want somethijng with an omnidirectional pattern, or a mic with a selectable pattern. Used mics are a bargin and ususally the older the better. Look for AKG, Audio Technica, Sure, Nueman and Sony. They all made outstanding mics. I usually go to a session with a couple of omni's and at least one directional, depending on crowd noise. You can usually get good stereo and soundstage by monitioring one or two songs. From there its just set back, listen and watch the meters.
I have used boards in the past or even in some cases just plugged in to the exisitng souond board, but don't be afraid to just record straight to the deck. It's made for that and the ReVox has an incredible 24db of headroom. Thats the highest for any consumer deck.
Obviouly running a 15ips is best for recording live.
Norman