Yes non-AKV owners can book there as of June 6th. Based on reports here, non-owners have been having good luck at the 7-month window.
I don't know exactly how many 2BRs will be available as of Mar '08, but it's possible all of Jambo House will be open by then based on reports that construction is ahead of schedule. The original date for completion of Jambo House was May '08. Based on what we know for sure, the following "trails" will be open: Zebra, Giraffe, Ostrich plus the rooms around the lobby area. At least part of the Kudu trail should be open by that time, but I wouldn't be surprised if all of Kudu is open by then, in other words, I expect all of Jambo House will be open by that time.