It's an old post I thought for sure someone would have answered..
#1. Penn's red fingernail on his left hand is in the memory of his mother. She always told him to have clean hands since everyone would be looking at them. He wears his father's wedding ring as well.
As for your 2nd question I don't know.
It wouldn't have been a big deal if you asked them during the meet & greet after their show. Penn & Teller love it when us fans talk with them after the show.