Took awhile to reply so I'll try to answer everything at once.
I just thaw mine in water. I never did it in a ziplock bag. The biggest downside is that a wet rat does get colder faster. Do you recommend keeping them dry?
About dipping the the head in hot water...define hot water? I thaw mine and run them in water that is from my sink, but at its hottest. Is that enough?
That Dawn soap thing is REALLY WEIRD. Lol.
I have pet mice who live with ASFs, so I can use thier dirty bedding for scenting.
I do a "zombie dance", however I do it by holding the very tip of the rat's tail and just jiggling it ever so slightly. Enough to draw attention but not enough to scare the snake. If that doesn't work I leave it. It never fails for my original 6 boys.
Last but not least, technically no rats go to waste, as ones that are not eaten I cut up with scissors and give to my turtles. But I don't buy the rats for them and they get enough meat as is. As for buying more snakes...don't tempt me! ;)