I air dry with it. The first time I did it I plopped for 45 minutes and my BSL hair took a total of 4 hours to dry (including plop time). The second time, I used a little less water, plopped for 15 minutes, and my hair took a total of 3 hours to dry. But in both cases, the sides were dry enough to SOTC after 2 hours.
I agree with what msgiblet said about diffusing - you can get more volume with your hair if you diffuse than if you air dry. But I prefer less volume so I don't mind. I think my hair looks too messy when it's diffused - I get more definition with air drying. If I wanted a little more volume with the super soaker method, I would clip the top of my hair while it dried.
In answer to your other question, I use more base product with this method in case some goes down the drain.