The concierge rooms will be 2BR lock-offs, meaning they can be separate 1BR and studio, so you are not precluded from a studio. However, with the low number of concierge rooms what you may find is that other members may quickly gobble them up as 2BRs.
Jambo is the only building open until 2009. Also there will be no concierge rooms and no value rooms in the new building that will open in 2009.
I believe you can request savanna view for value but it is not a request that is guaranteed. However, for Sep 2007, an issue may be whether any of the value rooms open by then will even have a savanna view.
I would assume that by now Sep 2007 (for which there are no concierge rooms because those do not open until Dec) is pretty full but you won't know until you call.