Last year I stocked decent size crappie, sunfish, small bass and y. perch. 3 large hybrid carp were stocked long before the other species. Last year sunfish came to the shore near me and went after bread balls I threw. A bass would come by to see the commotion. I've only caught sunfish and a perch. Nothing else. At least I'm seeing fingerling fish (not sure the species).

Heron drop by and one killed a 12" bass leaving it on the shore dead. Could heron be killing the other fish when I'm not there? Would fish that die in the water necessarily float to the surface?

Pond is 8' deep in general with an in-flow pipe from some forest wetlands but it only supplies water after downpours. Rain is the only source and two years ago the pond was only 3.5' deep after a prolonged drought.

Yes, and no. Especially if their swim bladder was punctured.