Don't know anything on glycerol so I can't comment. It's hard to find Q10 without additives, but usually the benefits outweigh the issues unless you have specific allergies/sensitivities.
One thing I wanted to caution you about is to not add anything with the clay. What clay does is absorb retain and excrete. Anything you add with it hoping for other benefits gets absorbed and excreted just like the bad stuff.
It won't harm you, just a waste good supplements/money. In general don't take any other supplements with 2 hours of taking clay internally.
Why is it difficult keeping the clay between the cheek and gum of the infected tooth? It CAN be tricky getting the clay to the right consistency so it stays there.
The clay should be all moist but also dense enough to roll them into balls, etc that you put in the cheek. Of course during the day depending on your job you may or may not be able to get away with it anyway.
If I have an abcess or toothache, I make it work.
You can make it dryer still. Mine usually stay in place for several hours, even overnight while I slept (or didn't as the case may be). In fact as long as it stays in place it can't be too dry as the saliva will moisten it.
The only problem with adding things to clay is the clay absorbes and doesn't release it - so you get no benefit and is a waste of money. Not that it's harmful.