I'm thinking of getting tropical land snails, but I decided to practice with the regular garden land snail. I have three, in a 10 gallon tank and I feed them lettuce, cabbage, bramble, yucca, phormium, brassica, hosta, sedum, strawberries and apple. They eat a lot of stuff, but that's their favourites (and often were you can find them, too!)
They are in a quite damp tank covered with woodchips. I have little water bottle lids each filled with a different kind of plant and one filled with water for them. Unfortunately, they often end up tipping the bottle lids over with their 'one foot'.
They are not completely herbivorous, though, as they are often detrivores, so I sometimes feed them dead bugs and worms and slugs that have unfortunately been in the sun to long or snails killed by those menacing song thrushes.
Snail poo looks like a tiny green, stinky string, and you can 're-feed' their poo to the snails, since it still contains lots of wasted nutrients, much like some herbivorous rodents and rabbits.
I clean them out now and them, especially when they poo on the glass.
I'm thinking of adding a few woodlice that can help get rid of the poo quicker, so I need to clean less. I heard woodlice have pretty effective digestive systems in comparison to snails and also poo less.