For detailed info on CSI status you might be better off asking here:
http://forum.alpha-star.org/hardware/optical-sensors/#post-33
From the replies so far it is clear that the CSI interface is supported but has only been tested with cameras (meaning you might have problems with a HDMI to CSI convert since this will introduce new (at potentially unsupported) video modes.
For the later question, whilst I personally suspect Linaro may end up doing to work on the board the work it will be on a as-needed-for-development basis (the board has several unique features), there is not a formal programme of hardware enablement by Linaro for this board. Thus there are also no plans for a Linaro-supported Debian release or Linaro-supported Yocto layer.