Is that mold?

Correct.........mineral/salt residue.......not mold.........no need to do anything.

Nope just keep going. The white on the fabric pot is most likely mineral build up from the fabric pot getting extra moist and then drying out.

Molds tend to be fuzzy and this looks more like mineral deposits. Molds also will have a smell that can be rotten or sharp. You essentially "flushed" your plants. Don't know if it was just water or a nutrient solution they got flushed with, just confirm they have nutrients left in the medium after that kinda watering and they should bounce back just fine.

I'd say oxidized nute residue, but hard to tell

salts build up

Looks like some small roots to me. Probably the wet pot was softer and the roots had it easier to find their way through. Just by judging the picture I would say "everything fine".