First, no your ISP cannot see anything if you are using a VPN. They only see encrypted packages and might be able to determine that you are using a VPN but they absolutely cannot tell what data you are sending or receiving.
Second, I have never experienced that a ISP in Germany throttles torrenting, even without VPN. Torrenting per se is not illegal, you can download Linux ISOs via torrent. We still have net neutrality in the EU and in Germany. Throttling torrents would violate net neutrality and would be illegal AFAIK.
Your first and second points are incorrect.
First, no your ISP cannot see anything if you are using a VPN. They only see encrypted packages and might be able to determine that you are using a VPN but they absolutely cannot tell what data you are sending or receiving.
Second, I have never experienced that a ISP in Germany throttles torrenting, even without VPN. Torrenting per se is not illegal, you can download Linux ISOs via torrent. We still have net neutrality in the EU and in Germany. Throttling torrents would violate net neutrality and would be illegal AFAIK.