[Perfectlap]

1-don't do any wet sanding until you have exhausted every method possible with the PC orbital and a pro detailer can't do the job with a metabo rotary. The margin of error is slim to none. Given your unique color, I would not try anything you hadn't done before.

2-I'd a gone with Menzerma Intensive Polish for deswirling a black car. Optimum's line is also good with the PC. Poorboys is great but you'll have to work allot more to get the same results for the 1st time deswirling. Maintenace is no problem for the SSR's.

The misus is the only car I will do for free and even then I make here help me wash, clay, polish, seal, etc. That way she will see its allot of work and take better care of the car. Most women I know never care for their cars, very sloppy.
I'd do the same with your pal, make him help you if not he should fill your tank!
Deswirling is mucho work because you have to move slow, very slow with the buffer to get out swirls.

Funny how people who never wash their cars always want black cars. My friend who has had some of the most heinous looking cars ever, toxic waste sites really bought his first nice car. Acura TL what color? Black. oh dear...

p.s.
Tell your buddy to try Optimum No Rinse. I think its the way to go when washing a black car that is probably washed 300% more during its lifetime more than a car in a lighter color. More washing = more swirling.