thank you for your kind and comprehensive answer!
Regarding point 1) I still have problems.
Our internal Docker registry is configured with HTTP, a self signed certificate, no user and no password. Due to the NGINX server configuration, it must be called through its name, not with its IP address.
On the other side, it seems that the CF stager is able to resolve DNS names only by means of the Google public DNS server (188.8.131.52), so it cannot resolve the name of our internal Docker registry server.
Is there a way to configure Cloud Foundry in a way that it uses our internal DNS server instead of the Google one?
Thanks in advance.