#1
I plan to use a mic through my POD gx.

Which mic would be good to do that with?
#2
I think you can use any dynamic mic with that interface if you plug in an XLR - TRS adapter cable.
I would normally suggest the 990 and/or the 991 but those need phantom power which the GX won't supply.

I would get the 991 and an external power supply unit. The problem with dynamic mics are you have to turn the gain up a lot and the GX will add a lot of noise to the mix.