Mouse pointer size problem
You can set mouse cursor size for the user running lightdm. In my case it's root, so all I have to do:
echo "Xcursor.size: 24" >> /root/.Xdefaults
Hopefully it helps.
i had the same issue after changing from gdm to lightdm. my solution was to revert back to gdm and now my cursors are fine. to do this run
sudo dpkg-reconfigure gdm
and choose gdm as default.