It's good practice to re seat the brushes to be sure that's not the issue. I've had one GG polisher stop working (G21) and I removed the brushes and put them back in, and 2 years later still working perfectly.
The assumption is that you are looking for some correction ability in the AIO prior to the coating. If that's the case then just go with a polish instead of an AIO and save yourself some trouble.
No, you can't use an AIO before a coating, the paint needs to be completely clean and free from any polishing oils and waxes/sealants, otherwise the coating won't bond to the paint properly.
A light underneath it on the trigger side would be more beneficial IMO. I guess they got the idea from that company that made lights that attached to the sides of polishers.
I've never used the Costco brand towels, but the Sam's Club towels are perfectly fine for every use on any car. I have a suspicion that the Costco brand is the same exact towel, but I've never compared them to confirm.
I'm not sure, but in the situation of using it with a rinseless wash, I would spray very carefully and not just all over the entire exterior as you would normally do.
Sounds like the polish dried quickly while polishing and the residue hardened and didn't wipe off. Try a very quick polish again over the foggy areas and see if it is removed.
I'm curious what the different variants of the Scangrip based lights will cost compared to the actual Scangrip lights.
If the Megs coating is rated for around 2 years like almost every other coating then it'll be worth a try.
And we're still waiting on a direct iBrid competitor from Griot's.