I use warm water or even tank water to thaw them completely. They pretty much go straight to the bottom and easily get distributed by the current. Though in the angel tank, they rarely last that long.
I always let my frozen foods float as long as they can, once one of my fish drags the food down or it melts it all gets sucked into my filter Almost always it kets eaten quickly though.
Yup, use a little cup of tank water to thaw it. I strategically pour some into the front of the tank, to get the swimmers going, then the rest into the filter output flow to send it straight to the bottom in the rear half. The cories get more then their fill. As an asside, one of the cubes is a LOT of bloodworms, half a cube is plenty for a 30ish tank, 1/2 does both my tanks once every 4 days or so. Start with half and see how it works out, I even keep a little ziplock in the freezer to store the 'other half'.
I haven't met a fish that wont eat them yet, though, you just don't want them eating too much. My GBR gets greedy, Ill see him sitting in the corner hiding after a worm drop and suddenly blow out 10 of the things and start to try to collect them again. A betta that gets to too many will have to be put on a diet for a week, they will eat every single one they see. So start slow and see how fast each fish can get to them. You will definitely see nice fat corries after a feeding of those Also, make sure you wash your hands thoroughly after handling them, you definitely don't want to accidentally rub your eye or something later.
I buy frozen bloodworms from San Francisco Bay Brand that come in little pre-measured one inch cubes. I place the cube in one of those feeder cones that attach to the tank with a suction cup.
As the worms defrost they sink to the bottom of the cone and the fish can pick them out of the holes in the cone. I have less waste that way.