I sprayed 2K primer (Omni) over etch. Is it ok to wet sand when I block the 2K? (ie, will it absorb water and cause rust underneath or does the 2K seal out the water).

Also, in places that I sand through the 2K with 400grit and want to put on a couple more coats, do I have to rough up the 2K or will it adhere to 400 grit sanded primer? If I do rough up again, what grit will allow the 2K to adhere? Thanks

you can wetsand it and it is ok to recoat over 400 grit. Any places that aren't accessable with sandpaper should be scuffed with a red scotchbrite.