One of those good news/bad news stories.

[CaptainTruth]

1. Your plan sounds good, I would just add one thing.

I find mold pretty regularly when I remodel bathrooms, or when a customer has a leak around a window etc that lets moisture get into the wall.

When the wall is open, after I've scrubbed away the mold (usually use a bleach cleaner) & let it dry, I spray the inside of the wall with Concrobium Mold Control (available at Home Despot) before I close it up. Just soak it & leave it, don't wipe it off, so it will help prevent future mold. Don't forget to spray the back side of the new piece of drywall, too.

Once you're done cleaning/painting the exposed surfaces, you can spray them & let them dry too, before you put the DW back.

Good luck!