Yes, it is. The NFS server refuses to start if any of the directories to export is missing.
In your case there’s likely a share configured for that directory in the UMC (“Domain” → “Shares”). Just remove that one share, and the NFS server should start up again.
Yeah, those can all be removed. It’s possible that there are configuration files lying around from packages in state rc (removed, but config-files present). See the output of dpkg -l | grep -E '^rc.*ucc' and if that looks fine, purge them with dpkg --purge <package1> <package2>… (or the somewhat dangerous but automatic dpkg -l | awk '/^rc.*ucc/ { print $2 }' | xargs -r dpkg --purge ).