Q: Why he has a band-aid on his face?

A: Andy's main setting is him living in a spacecruise, or even in a space station full of clones of himself and so the reason of why he has a bandaid covering his right facecheek is to hide his green trefoil "birthmark" plus the clone number he is. That gives more artistic liberty to other artists willing to draw him(or female version) without worry about thinking the clone number they're drawing.

In other more primitive and medieval-fantasy settings, his clone number is wiped but he remains hiding his birthmark under the excuse of covering a scar.