The problem is that My tank is about 1 meter tall and its not very easy to reach down without completely wetting myself or getting bitten by the fish. It could be snails, but I couldnt find any identical pictures on schroogle to confirm it.
No idea. I have always had hundreds of them and never seen anything come from it. If so, I would have thousands of Nerites . Not sure if they just dissolve or get woofed. I would guess that the environment in the tank is not suitable for raising them.
If you have interest in it i would think it could be done in a small tank (like a 2.5 - 5 gallon).