After applying AIO and letting sit for a day (or two?), do I definitely wash, definitely do not wash, or simply judge if needed before applying AIO coats?
You should wash, but make sure that you dry very well, as the directions on the SG say that you should use a dry pad. I assume (I know, I know ) that this means that the vehicle should be totally dry as well.
You should always wash your car before applying coats of a wax, polymer, etc. If your car is relatively clean, then just use very little car soap, or practically none. Quick detailing just doesn't cut it. Laters.