4 headsets and a mixer

Unexpected success. This is the battery adapter box you need to plug a “computer” headset into your mixer.

http://www.kozco.com/tech/audacity/pix/headsetBattery.jpg

I don’t know of anybody that makes one, so you have to do it.

This is the thread from someone who wanted to do something very similar to what you’re doing. It’s a very serious thread.

https://forum.audacityteam.org/t/problem-using-pc-headset-mics-with-a-yamaha-audio-mixer/23522/1

The headphone system can be simply an octopus headphone adapter.

http://www.radioshack.com/product/index.jsp?productId=2102960

Four people is harder. Do you have a mixer picked out yet? I recommend the Peavey PV6 only because they’ve worked well for us and they’re not a million dollars.

http://www.sweetwater.com/store/detail/PV6/
or
http://www.sweetwater.com/store/detail/PV6USB/
You need to know that they’re not battery powered and you’ll need that later for actual tail-gaters.

Many people who do this use portable recorders, not put-together systems. Zoom, Marantz, etc.

Koz