Don't worry about the lack of airlock activity, I don't get any through mine. As long as you've got foaming (krausen) at the top, the yeast is doing its thing.
In my limited use of pressure barrels, it's been the tap seal that's been the problem. Never thought of using ptfe tape, first time using it on this brew and no leaks!
Cheers for the write up 👍
Yep, true. I do have a 15 litre stainless pot that I could use on the hob. I'm just future proofing for big beers, and 30 litre for the same price as 19/ 20 appeals