For pads to polish a car it depends on the car and the polish.
For instance a swirled-up car might call for an aggresive pad and polish combo. Combinations of light polish and aggresive pads can also be used.
I tend to like orange pads with more aggresive polishes and green pads with lighter polishes and "All-in-ones".
Pad colors are not the same accross the board and may vary in "bite" from one manufacturer to another.
I generally apply and remove sealants by hand. IMO the PC wastes too much product. I can cover a car three times with less than 1/2 oz. of Zaino.
The only wax (sealant) I have applied by using the PC has been "Insulator Wax" and Poorboys EX. Both were removed by hand.
A black pad is generally the pad used to remove waxes / sealants with.