I feed mine Silversides once every two weeks. However in your case it would best to feed small pieces (no larger than the mouth) every 3-4 days. As for the deflation, occasionally mine deflates (1 time a year) and it moves when the MH lamps need to be changed (12 months). The anemone looks good, keep it up high near the light and keep up with the feedings.
I have had my ritteri 6 1/2 years just in case anyone wanted to know.