I feed my neons once a day, you could probably feed them more often if you want but then you'll probably end up with more left overs.
As far as snails for a cuc, mine don't seem to do a lot, I mean every little bit helps but I wouldn't depend on them, would probably need a bunch to make a noticable impact, but then you have the problem of them over populating.
I'm not having much luck with cuc on my new 47gal. I have cherry shrimp, a couple of snails (one adult and a few babies that crop up from time to time) and one algea eater. Thinking about adding cories to take care of the food that hits the bottom.
Still debating on adding a few freshwater crabs, but then I couldn't get the cories so I don't know.