How to reveal original paint?

[2bo.c10]

Hi Everyone, THE PO got a really bad paint job - Some areas look like it may have been rattle canned, and others look like it may have been rolled on. There is a really cool green color that is under it which I believe is original (when I remove the headlight bezel, Its around the headlights). I would like to remove the crap paint which is the top layer and reveal the original paint - or whatever is under it.

Can anyone provide any advice on what I should do? Should I wet sand with 600 grit? DA Sander? Dry sand? I really don't want to use chemicals as I have a small garage / alley to work with and disposal is a pain. Also - the exposed paint is so bad, and so poorly bonded that if you brush up against the truck, it will leave a white mark on your clothes (the truck is white).

Also, when sanding - any advice on what respirator I should wear? Here is the link to the one I currently wear for other things - will this work?

https://www.homedepot.com/p/3M-Mediu...A1-C/202080144

Thanks in advance!