I'am not sure where to install Calender Server and to which networks open
the port. Documentation is somewhat short on information for a decision...
somebody has more information on this?

Does it make sense - from a security point of view - to open CalDAV/CardDAV
to the internet?

Is it possible to access CalDAV/CardDAV through a reverse proxy (apache)?

That Admin Connection from Calendar Server to GroupWise - is it only needed
for initial configuration? Or is it permanent? Is the admin passwort stored
localy on the Calender Server system?