Yes, opensource and a free to use license. This makes it possible to use one design for both small and large infrastructures. This idea of standardization is one of the key factors in the Hannibal project.
Yes, all user authentication is against LDAP, and preferably also extra needed application roles.
Not at the moment. There are some projects busy wit it. When a good shared-calendar product is available in opensource, it will soon be documented.
It will be when someone volunteers to do the research to make it work, and to document it.
Yes, sponsor the software part or parts directly, by using the sourceforge links, or let your Commercial supplier arrange the sponsoring to the software developers for you.