thats a great sign that they are eating like crazy. They are beauties! if you have problems with them taking new food usually mixing it with some food they already take can help, with my bloodworms (frozen) i actually put them in hot water to defrost then add them slowly to make sure they get eaten and a huge chunk doesnt get stuck under plants, also very few float then. so try soaking them in a cup of water before putting them in the tank, should help resolve the floating.

let us know how you go with it