I am not a water snail expert, but first (obviously) I know that they are snails that live in water. These snails will dry up when they are outside of water, and when they escape, this usually means the water they are inside is dirty, so check your water quality if you are a water snail keeper. I sometimes call these water snails aquarium snails, the ones that are sold in petstores. There are Mystery snails and Apple snails in this column.
If you mean the type you can get in aquariums - see the link for the Wikipedia article...
yes, watersnails can have a babby, want proof? well last night my watersnails had 2 babby's when there born there really small you can hardly see them
Yes they can ! You might find a water-snail in your aquarium - but it may have already laid a large number of eggs - which will hatch into tiny snails !
many amphibious (water creatures) species live there. It depends if it is a fresh water river or a salt river. If fresh water, i think frogs would live in the water, many birds also live near water picking off what animals they can (crabs, worms etc.)