Well it's to do with the glibc upgrade and the findutils package.
I'll have a talk with PiterPunk and see what we can do about it but I think using
slackpkg -dialog=off upgrade-all
May be a work-around for now
Yes upgrade slackpkg but do the findutils upgrade manually first. (use upgradepkg for findutils) Followed by a slackpkg update.
Those gpg errors should disappear and with luck your kde4 should be fixed too.