Here are some theories

First the Rock Lee ones
1) All Lee needed was a surgery that would remove the bone fragements from his spine right? Well why not just get a Byakugen master (or even hinata) to percisely hit them and destroy the fragments? the surgery would be done in no time and Tsunade can heal people quickly or Lee could just open the life/wound gate or whatever..

2) The surgery failed and Lee is now a ticking time bomb, with the last of his energy hes gonna help the others (maily to make Sakura happy) hes opened up gates and is about to fight (kimi is in a similar situation as well... would make for an interesting fight)

Rescue Team Thoeries
1) The team consists of Lee, Tenten Shino and Shizune. This team makes the most sense imo.. all fighters and what not. (Ino, Sakura and Hinata would never be part of the team imo)

2) Shino's mission was to track down Sand nins. The reason is that the Leaf need help (they are short handed) and the Sand pretty much owe them a war debt for surrenderring. Its quite possible we could see Garra joining the fight but not on his own free will. Hes getting forced to help so to speak

And those are my theories...