One thing about licenses: the names are kind of long, instead you could just name them "CC-BY(-SA) 3.0", "GPLv3" and "PD" etc.

Also I recommend to instead of just "public domain" to have the choice also include the CC0 license http://creativecommons.org/publicdomain/zero/1.0/ so it will be "PD/CC0" - this will make it easier for distributors for non-US legal reasons.