Cyane,
No bother. I'm enjoying this. Hope you're learning something.
I still say the best overall ozonator for you right now is the Nature Kleen. It will do air,water, and if you put a fan in front of the ozone bubbler, it will spread the ozone around your room. It's a good as any other small ozone product you'll find for the money and much better than most.
I think I covered the second question fairly well in the last post except that perhaps for convenience of portability and ease of use which an air-fed machine provides, it lacks the purity, higher concentration and numbers of uses that you get with an oxygen fed generator.