No the buble won't grow back.
Newer strains have many segmented bubles so that if one pops there is still
some bubble left.
They don't usually compete well at all if they are good sized bubbles. Do
well on birneshrimp and frozen peas as well as flake.
maybe try blood worm for the betta's. My betta's love brine but they are
known for being drama queens.
When fish are not hungry it can be a good time to water change.
Healthy fish is a hungry fish espec if you have him at a high temperature