So you are saying that this Numark with USB I/O won't work for me? It seems like it's what I need.
from the description, it looks like the USB mic may work. (obviously i haven't tried this). doesn't seem like an ideal sol'n, though, except as a way to justify the purchase of the USB mic.
the mixer does have inputs for a "normal" mic, though i don't see phantom power so it would probably be a dynamic, like an sm-57.
if the USB mic did work as an input, there'd be no way to control the amplitude of the signal coming in. unless it's a good match, you'll have to compensate at the mixer, either by turning down a hot and possibly distorted signal, or trying to bring up the level of the signal. could get nasty.
finally, i didn't see any indication that the signal would stay digital all the way to the computer. it'd be kinda silly to convert a/d, then d/a, just to a/d it into the computer, as hakukani mentioned.