I think quality levels are roughly in this order, from best to worst:
1. Steven (blue snowball)
2. Wahrer (blue snowball)
3. Austin / Ghazi (H1 mic / Etheric Ore)
4. Ian on mic
5. Tyler, Ian on mobile phone (potato)
I thought I had leveled out the audio for the most part save for Tyler's, who's kinda difficult to modify due to how small the dynamic range is in his recordings. That being said, I typically have everyone possible record themselves as well and only use my personal Mumble recordings if there's no other option available and then send over the individualized stems. Levels may be due to a different mastering setup I used for this one, so I'll have to play around with it.
Popping for the most part is edited out manually (only Steven and I have pop filters iirc,) but I'm usually pretty good about noise removal and editing out the "blank" parts of the individual tracks. Ian was sitting in what sounds like a fucking rocking chair for RR7, though. I blame him.