SOME people want to ask for advice but want to hear what they want to hear not what honest advice you really have lol.
SOME people cannot take honesty, they take it personally and/or get offended.
SOME people feel the need to be rude and defend their f*** ups instead of just owning up to it and taking constructive criticism and advice.
SOME people are ridiculously immature and are unable to have a conversation or debate their opposing opinions (especially about touchy topics) without calling names and being rude to get their point across.
Guys tend to go on more senseless ranting than girls do on here. By ranting, I mean long, monotonous bashing of a subject that goes on for several paragraphs. The person then praises the people that agree, and has a flame war with the people that dissent. Guys also ask more political questions.
If I post something in sexuality that is detailed, I all of a sudden have like 5 more friend requests than normal, and all guys. My profile says happily taken, I don't want to flirt with you. I don't wanna talk on Skype with you. etc.
As to your points I would say girls are generally more inquisitive when it comes to relationship advice, and since those questions are largely addressed towards guys, more guys are likely to answer those questions... This is Girls Ask Guys after all. I agree many anonymous posts are trash, thus why they get less replies.
Most of the questions I answer are posed by girls. Girls tend to ask questions with as little detail as possible or with fictional scenarios that kind of represent what they want to know. It's like they are being secretive and don't want to expose what is really happening. If you drag it out of them through conversation they will eventually tell you what is happening, or will contact you in private and spill to you and you alone if you have their trust.
Guys on the other hand tend to ask very direct questions that need no further investigation. You can give them a direct answer and they can walk away with what they really wanted to know.
Both sexes post tons of vitriol. I'd say the amount from each sex is about even, there are just far more questions from girls so it makes it easier to answer a number of female questions.