Hi, Bill. I don't usually use separate audio software since so much is built-in to Sony Vegas Platinum. You can adjust the volume in there as well as tweak EQ settings and the like.

For my "book case" audio, I use a cheap ass Radio Shack lapel mic hooked directly into my camera. I think this is it, but not quite sure...Anyway, it outputs in mono, so I just select "left channel only" in Vegas and that puts the audio on both channels (no need for an adapter that way). I find that if I just use my camera's mic, you hear a sort of "cavern" like sound in the audio.

For narration, I use a Sure SM58 with a little slip-on windscreen like thing. I went overkill with an M-audio Pre-USB thing that I certainly didn't need (I stupidly thought that "phantom power" meant it would boost the mic like a pre-amp, but was wrong about that. I'm not sure what I'd recommend over that, but ideally just a USB microphone with really nice quality. The headsets I've tried just lack in that department with a tinny sound. Something like this or this would probably be overkill, though you'd almost certainly get great quality. Here's one for $50 that looks good.

Not sure what you'd need another type of mic for unless you really hate seeing the clip-on or want to record sound effects or what have you.