Greg responds...

SPIDEY SPOILERS!!!!

1. I think physical trauma from the "accident" played a part, certainly. But I think subconsciously, the key moment is when he cries out, "But I've been good!" right before the explosion. Now, (a) one could argue he hasn't actually been good, but (b) from his point of view "good" means obedient, subservient, nebbishy. And his "reward" for that behavior is, well, <BOOM>! So his mind rejects his past behavior entirely and does a complete personality 180. Otto Octavius was ALWAYS smart enough to be Doctor Octopus. Now he had the mindset to go with it.

2. Wouldn't Spider-Man like to know? (And you too, I gather.)

3. You forgot Electro and Kraven. Anyway, I don't think the specifics are too important. But I imagine that Rhino sank to the bottom of the river (putting on the oxygen mask/tank that Spidey gave him) and slowly WALKED to shore. Then busted Sandman out of the ice. Tinkerer had some of the Master Planner's men cut a hole out beneath Vulture and cut Electro out of his rubbery confines. Kraven, I think, just slipped out during the confusion.