1: Raph has trouble reading; he has a learning disability -- he's not stupid, and sometimes he's a slow thinker, but it's because there's a genuine mental block to his ability to learn. His frustration with his ability to keep up has him slacking off a lot. If it were diagnosed and treated, he'd be humiliated, but might get back in the saddle and try harder... or he might just hide further.
2: Raph's journal is written mostly in notes to his brothers and Splinter, occasional things he wants to remember -- but his writing and his spelling is atrocious. His memory is excellent, however -- the journal is mostly for him to try and work out problems without having to to anybody else for them.
3: Raph loves his heavy metal; his CD collection is comprised mostly of Megadeth, Metallica, Ozzy Osbourne, Pantera, and the like. Hard, classic metal. It's supplemented by Industrial as it comes into style, and some classic and psychadelic rock. (Pink Floyd, Jimi Hendrix, so forth.) However, few bands will be as well loved as his core of metal.
4: Raph doens't want to
lead his brothers. However, he's a very capable lieutenant and protector. Leo couldn't do better for a second in command. Raph will always make emotive decisions, however, and struggle with the rational ones.
5: Raph's hangups with gays are a fear -- and just a liitle fearful curiousity. He's not gay and he'll never be bisexual. That's a mammal thing in his brain, and mammal sex is alien. Hell, human sex is alien, and there's no other sex to learn about
but human sex. It's intriguing, disgusting, frustrating and wanting, but it's what he and his brothers are conditioned too by living among mammals. There ARE no females of their breed, nothing to develope their own attractions with... and while mutation has brought them to a midpoint between reptile and mammal, it's still going to be slightly off, not quite
there. But it's what years learning from watching and wondering has told him he is supposed to be attracted to, so he sort of is. (Weird side note: Raph prefers blondes.)