Coco fiber for substrate, gravel and moss can and have both caused impactions as well as deaths in pacmans. Babies should be offered food daily, and then cutting back as they age. As long as you don't saturate the substrate there should be no mold problems, and with daily spot checking the tank you can go for several months without changing the substrate.

Both male and female will chirp and grunt when aggravated or uncomfortable, but not loud enough to bother you in another room.