How likely is is that a cherry shrimp will eat another?

They're very likely to eat a sick and dying shrimp (which you should allow if it didn't potentially die of illness) but they're mostly scavengers. They won't readily eat any fish or other shrimp that's alive and well.

They will never eat a shrimp that is still alive, if one dies, another will eat their corpse.

More likely if you don't feed them properly.

it wont, itll go on top of ice-crem duhhh