Your BADSIG Problem is an easy one. Your signatures are incorrect. Update them with:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 40976EAF437D05B5
Please do that with every wrong key by just changing the last key number and keeping the rest.
Rebuild your software cache:
cd /var/lib/apt sudo mv lists lists.old sudo mkdir -p lists/partial sudo apt-get update