Dont worry about "defrosting incorrectly". Really, there is nothing easier.

Dunk the rodent in warm water. Let it sit until defrosted thoroughly. If it's a large rodent, dump out and refill the water once chilled.

Some people defrost in bags. There really is no need to prevent water from touching your rodent. I mean really, it's water.

I never feel guilty about feeding live, but for me it isn't necessary. I've never had a snake that refused F/T.