you can feed silverside, smelts, fish fillet, shrimp, etc. if too big then just cut to the size that it can swallow.
not sure if their teeth will go back, I would guess they will. they rely on teeth to grab hold of their prey and often get damaged. if they don't grow back the fish will eventually die from loose of teeth, must have a way of dealing with that issue. could be completely wrong tho...maybe other with more experience can answer you better.