The forearm is the most requested placement for a single portrait, and the one most often done at a convention, because a well planned forearm portrait is a realistic one day piece.
It is also the placement you will look at most: it faces you, all day, for the rest of your life.
On a forearm, usually yes, if it is one face at a sensible size. Two faces, or a face with a detailed background, is two days.
Smaller than roughly a hand span and the detail that makes it a likeness starts competing with how ink spreads in skin over the years. He will tell you if your idea is too small before you book it.
Outer if you want it to heal easily and hurt less. Inner if you want to be the one who sees it.
One sharp, well lit photograph. Good light on the face beats high resolution, and both beat a screenshot of a screenshot.
Requests go straight to Federico, not to an agency inbox. He answers from his own address.