Q1: I dunno...I got the score on my first try (Or at least, the Oathkeeper), so I'm not sure. Gimme a few minutes, I'll give you the score I got. EDIT: My score was 1976. What was yours?
Q2: You have to get all the cards. Normal, Extra, and Alternate. I'll tell you right now, unless you're a Platforming Pro, Hollow Bastion's extra is the hardest to get. Speed Run is an understatement.
To get it, you have to Beat Pete in under 30 seconds in part one, and complete part two in under 50 seconds. It is not easy.
Q3: I bet you can if you replay the episode. Roxas is probably under Score attack, too.
just wait until you get glide. Then you can laugh as the second challenge in HB becomes a 10 second glide fest.