A: The best Japanese singer/songwriter, that's who. Matsutouya Yumi, nickname Yuming, is a veteran of Jpop, made her debut in 1973. She writes practically all of her songs herself, both lyrics and music. She produces an album about once a year.
A: She has a voice like cool cherry yoghourt, rich but not greasy, with a lot of sweetness complemented by a certain acidity and dominated by a strong characteristic flavour. It has the forced, slightly nasal character which is one way for Japanese singers to sound. There's none of the high pitched, overly cute Lolita-ishness which is the other mainstream of female Jpop.
A: Hey, take it easy, boys. She's not a major babe. Not even a minor babe. She's not the kind of singer you adore because of her looks. Rather the kind you adore because of her music. She likes to dress up, and hardly two of the photos on her CD covers and in the CD booklets look like they were of the same person.
A: My Japanese is not really good enough to entitle me to an opinion on that. You'll have to wait for my Japanese to get better or ask a Japanese friend.
A: Simple tunes. The kind that, once you've heard them a couple of times, you think you've known them since your childhood. Some of them are a little bit jazzy, but not so much that it could offend anyone. They all have the property that they head rigth for the G spot in your ears, drill through it and start eating your brain. (This may sound like something from The X Files, but actually it's a wonderful feeling and once it's happened to you you'll understand, you'll be one of us, you won't want to resist anymore...)
A: Yes, e.g. there's the official homepage maintained by her record company Toshiba/EMI. It contains a complete discography and sound clips from all of her songs. And there are a number of other sites (mostly in Japanese, I'm afraid) maintained by fans. The "Famous Personages in Japan" project of Kyoto Sangyo University contains a short presentation of her in English. Hong Kong fan Ray has a Chinese/English site with news and concert reports. There's an English language mailing list (Yahoo group) devoted to her and her music that you may/must want to join.
A: Lyrics, in romaji as well as kanji. I've tried to follow the BeroBero Rules of Romanization, except that one of the rules, the one about small katakana, stuck in my throat, so I'm doing that a little differently. (You'll see how. There's plenty of katakana in Yuming's lyrics). Also the BeroBero Rules don't say how to indicate stuff that was originally in romaji. I use double quotes for that.