Setting delegate permissions from a command-line tool: this has been added to the Zarafa Collaboration Platform packages starting from 7.1.0. It will be documented in the Administrator's manual. Update: this script is included in the zarafa-utils package starting from 7.1.0RC3.
Sizes configurable in KB, MB, GB, etc.: this was added to the core ZCP code, and will also be released with the 7.1.0 RC1 packages.
The result of the research of a live synchronization between Zarafa and Exchange is going to be published at a later time and announced in standard release notes.
Please note that the follow up QA processing might cause small changes or delay in publishing.