More or less. They'll eat any decaying plant or animal matter. Although just tossing in a green bean it will likely float for a long time. They've got a nice hook they can get it under there. Makes it much easier for the snails to get to. Lettuce is also another good thing for them.

I lightly cook it (microwave vegetable steamer works great.) and then toss it in yes. They love green beans.

Surprisingly, pretty quickly. Usually within a few minutes.

I know them as Devils Thorn snails. Very interesting guys, they can move pretty fast, even with that long shell dragging behind.