Welcome Blue!
To answer your questions, I have thought about the oxygen/breathing tube mask deal,,,I would think that the oxygen tube that goes from the tank to the patients face (over the ears, under the nose, and two outlets on the hose that go slightly into the nose...) would work good. I would imagine that while the fan assist might work, it could force to much vapor. It may not give you a chance to "clear the hit" and pull oxygen in after the vapor. If you used the nose mask setup i described above, with no fan, you could inhale through the nose for vapor, and then primarily through the mouth to get some fresh air....
I agree with you about the lack of need for stirring using the method you described...I normally use elbow packs for thicker hits, but when I'm just sipping the vapor, i use the method you described in the cyclone bowl.
As for the temps, I start around 185c and my max temp is 230c. The general consensus here seems to be that in order to get the couch lock effect that is familiar to combusting, you need to go to 220-230c. This should not burn, or even scorch your herbs, but will be hot enough to release some of the actives in the herb that give a sleepy couchlock effect. This is especially true with indica strains.