2/3. First off-- I don't mind playing as a female in a storygame as long as it's written well and if it isn't conceited at all. Sometimes it's a lot of fun. Playing as a male in an RP, however, is simpler for me. Kinda hard to explain, but take the Buffy tv show-- the female characters are female, dress, personality and all. An intriguing female character isn't just an interesting male character with boobs, it's a bit more than that. A female character who is truly complex isn't a plain, determined personality, and honestly you have to add more to a female character than a male character because of this (which makes sense, since in this day and age women are expected to do what men do and more, just usually not at the same time). Treading the line between "FeministNecessity" and "InterestingCharacter WithWomanlyAttributes" is a tough line, so I figure most claim they're fighting for equality by stuffing in genderless females when I think it's not.
Example;"Men" (stereotype) don't worry if their dress is too formal or not, "Women" do. Little things like that make a male character simply not have that sort of baggage. So basically a writer could focus on a teenaged male character's quest to save the world while having basic issues controlling his superpowers, his friends that expect him to conform, other social angst and the like-- while an actual teenaged female character (assuming it's a female modeled after the average teenaged girl) ALSO has to focus more exactly on the social pressure (make-up, jewelry, gossip, --dareisayit-- the time of the month)-- basically the things that girls generally have that boys don't, all in an effort to make the female characters real. Back to Sensitive Joss Whedon, Buffy isn't a feminist icon because she was interchangeable for a male hero, she became one because she kicked ass and squealed like my sis while doing it. (Disclaimer: I'm not even that big of a fan of the show. My sis watches it. I'm sure I'd like a character besides Giles if I paid more attention. It's just that aspect of teenaged characters I thought remarkable.)
Of course, if you're making blank-slates for either gender in a serious RP then you're doing it wrong. In a story (especially a CYOA) it's different because sometimes you want your readers to easily relate and act out what they would do in situation X, which is why COG makes such a big deal about it. Matters what kind of story you're making. That's kinda my take on it from whatever I've picked up. It's 4am so God knows if this makes sense.
Edit: Shit. Totally forgot about Secret of Daphne, which is probably the best example of this. Excellent game. Another example would be Babylon 5 (Ivanova was great even though they didn't ignore her gender-- it just wasn't the focus nor did it have that annoying conceitedness other things have when they try to be inclusive.)
4/5: I'm kinda confused by the last couple of questions. How do anime-like appearances translate to paper? Does it like, describe them as having spiky hair and a tendency to overreact? Besides that, if the story is good then the game is good. If it's a realistic game meant to be in our universe then playing as a female soldier (in combat) should be at least explained.