The answer to the question about a kohen hand being touched after washing for birkat kohanim. You mentioned it only if the hand was wet. Does it matter if its dry and someone else touched it?
Answer:
If the hand is already dry, there is no concern over somebody else touching it. Only a wet hand can be “mekabel tumah” from other hands. The same principle applies for netilas yadayim before food: one must be wary of somebody who hasn’t washed touching one’s hand while they are still wet.