Does the ink on the paper not effect them?
Modern newspaper inks are apparently harmless.
I don't know how selfish this is, but I like the natural, attractive look of the substrate, because it is in the living room (no other place for it), I dressed the tank up pretty snazzy.
I just lay a sheet of newspaper over the substrate when feeding and remove it after.
are younger mice an easier option? how defensive are hoppers?
I don't feed live so someone else here will be far better qualified to answer that one, but I DO feed in the tank. Very debatable subject though, this one!
Good luck!