I've applied it with my PC and my rotary.
With my PC I've used an orange LC pad, and white LC pads. I typically work it like I would a polish on PC at speeds 5-6. I'd much rather use the white pad than orange, but it looked like I got more correction (possibly filling...not really sure..no stripping wipedown as it was a one step) with the orange.
With my rotary, I've applied it with a blue Edge Polishing pad and a white Edge finishing pad. I usually keep the speed down around 1000, but I think I've bumped up to about 1200. I'd definitely recommend that you get a feel for the product with the PC first, because you cant really see it on the finish as well as with other polishes.
I've never left it alone on a car. I spritz a little OCW onto the panel as I remove the PS. I'm wiping it down anyway, so the OCW doesnt add any more time to the process, and it should give you some extra protection.