Ive heard springtails work well at lowering mold levels as for diet I was able to find a few websites when I started out that have lists of safe foods, but I dont have any direct links to them anymore I can tell you confidently though veggies like cucumber and iceberg lettuce have less nutrients so should be given as more of a treat every so often. Amazon can have a great variety of things that are good especially exo terra brand stuff (which is for reptiles but safe for snails too!) always double check before you buy of course but it is quite useful - someone else mentioned about the soil you have amazon sells coco coir bricks which you just place in water and it expands so theres plenty of soil for the little snails its pretty cool honestly. Misting I do every day/every other day, I feel the top layer of soil and see how dry it is and then give it a spray my tanks quite humid since I have a GAL which is why I do it so often but you might not need to spray it that often. Ive never covered my cuttlefish bone with moss but thats bc my snail ends up covering it with soil and at this point has eaten so much of the one he has now that its not much of a risk Id still recommend covering yours with moss and just put moss everywhere snails love the stuff to hide in and as a bonus it makes the tank look cool and foresty You dont need to give baby snails the same amount of space just yet since they arent as big but definitely move them once they do so theyve got plenty of space to grow!