4DSC, that's really interesting about applying SG wet. I've noticed that it spreads out much thinner with a little water too. Usually, this is added to it accidentaly from a body seam. Have you noticed that it gets a little harder to remove? I've noticed areas where a lot of water gets on the pad, the SG gets really gummy on the paint and gets dang near impossible to remove. But then once some of the water works out, it spreads easier and removes like normal. I'll have to try intentionally adding a mist of water to SG some time. Sounds neat.
The bottle says "contains no water" on the front, though, so I don't think it's water-based.
Polaris, #7 really doesn't do much more than fill in swirls and shine up the surface with oils. It doesn't really make a lasting change to the paint. Scratch-X will, though. The scratches it removed should stay gone.
If your swirls are minor, AIO and SG won't remove them, but they may minimize them. It may depend on the color of your car, and how big the swirls really are. My wife's car has full-coverage of light swirls, and I don't really bother with prep work on it (although I clay it). I've always kept it regularly protected, and used to use cleaner/waxes so the surface isn't oxidized or dull or anything, it just has a lot of light swirls. 1xAIO and 2xSG and the swirls are less noticeable than they were. But they are still there. If you want the swirls gone, you'll have to remove them. If you just want to make them a bit less noticeable and they are already pretty minor, you'll probably be ok. If nothing else, use AIO and SG and P21S to get through the winter (the P21S may help hide the swirls too). If you are unhappy with the swirling, fix it when the weather warms up.