wetsanding ?

120's way to course id start with some 400 and go from there. 120 will just put huge scratches in everything and then youll have to restart completely.

The little specs you are seeing are probably fish eyes, from grease, oil, etc. Wet sand with like 500 and get a good wax and grease remover and then spray away.

i used to detail for chrysler and mercedes a looong time ago....start off with the highest number grit you can get.....then work your way to a lower until u get the desired outcome...make sure you use soap...doesnt matter could even be dishwashing liquid just make sure the surface is very slippery...try to find something like a smal black of wood b/.c soemtimes use could be sanding an area then whn you done you see finger marks.....then buff it with course compund, then medium, the light, then a cleaner, then a carnuba based wax..should come out CRISPY!!...mercedes used to make me do that to there used cars everytime they got a trad in..i had to we sand the WHOLE car b4 they tried to resell it even if it had no marks on it!!.....