I always wondered what a feeding ring was for. I've seen them in the pet store, but never looked at them all that closely.
When I feed bloodworms (or anything else frozen), I leave them frozen and it sort of bobs around from top to bottom with worms/algae/shrimp flying off. The fish seem to love it. The gouramis and shark mostly hang back and catch the stuff floating around but the bars, pigs that they are, go and attack it, knock it around, drag it back and forth. The seem to be enjoying themselves.
As for where in the tank I put the food. I never really gave it much thought. It all moves around and floating or sinking, they find it within a few minutes anyways.
I always think it's funny when I try to give the pleco algae. I have sinking algae wafers. I'll drop one in, as close to his hiding spot as I can, late at night, hours after the lights have been turned off and then watch as the barbs sneak over, very slowly.