I think the only way Sora can remember what happened in Oblivion is that he gets his chain of memories back the way they were when Namine first changed them.
All I ever wanted from the city is more boss fights there. With Xemnas it only showed the main building in the fight. Which i didn't like but I still enjoyed that fight as one of my favorites.
This is a very very very hard choice. Axel I guess for many reasons. First thing him killing Vexen with just a snap of his fingers. His quote on quote "deaths". The relationship with Roxas <3. "Got it memorized" - Axel