I didn't understand what was going on in that naval battle. Wasn't Obi-Wan part of a fleet of ships? Grevious lands a dozen droids on the hangar deck and he considers the entire ship lost? It looked like the Seps were blasting the other ships apart; why would Grevious board the flagship with a Jedi onboard and not one of the less protected ones? As mentioned above, why would Obi-Wan warn Grevious to save his life?