So I want to have a set up where I can plug my pc audio coming from my pc's sound card via 3.5mm jack out, and the 3.5mm jack out from my microphone's mic monitoring going into the same headphones at the same time. My mic is usb and if I use windows to monitor my mic there is a delay, however my mic come's with a 3.5mm out allowing you to listen to the mic in real time.
It depends on the mic - I'll say probably not, and then you need something between the mic and the mixer unit. Just search for "microphone preamplifier" on the web, you'll find both units to buy and circuit schematics if you want to build one.
An old computer can be used too if you have one - just to get from the mic to a lasting audio signal, so to speak.
Well the microphone has an amplifier built in, I believe the 3.5mm jack on the mic is meant to be used as a a pass though from your pc, however although the amp in the mic is good it cant effectively drive my fostex T20's.