1.) I have issues with the Archive/Calendar view. When choosing a Month I get images from many different years/months. Does this functions search for Capture date or Modified date. It seems to be searching via Modified date. Since my whole gallery was uploaded at once, this does not work.
By Capture Date I mean "Date Time Original". The field is accurate in the back end.
2.) Also, the Archive view is not available to my regular users, even though they should have permission. Don't see where that permission would be denied, in settings. They have permission for unpublished photos, too.
3.) I'm using zpArdoise theme but I assume this is a function of ZP & not the theme.
You should try an official theme. If it does not happen there it is a theme issue.
I don't know anything about this theme so I have no idea about how its archive view is setup. On official themes everyone can see the archive and will see what his rights allow.