When you thaw out the rodents you want to make sure they also get warm enough that they resemble live ones. A cold corpse that is just beyond the stage of an ice cude will probably get refused. When you touch the rat it shouldn't feel warm or cold to you. I put them in a plastic bag, fill the bathroom sink with warm water and submerge them for awhile. After that I warm up their heads with a blow dryer to give the snakes a good target for striking.

Don't refreeze them. Only bad thing about frozen is you have to toss it if it gets refused.

Rat pinky is probably too small depending on how that is being defined by the seller. More likely you'll be looking for a rat fuzzy or pup, or a mouse weanling or adult.