^ Yeah, but the hair colors in most anime, including "Love Live!", were never meant to be realistic. Since Japanese hair color is so uniform (some schools literally make them dye it a particular shade), they indulge in crazy shades in fiction. Hence Rina's bubblegum color, and Umi's dark bluish, definitely non-brunette shade.
^ Hm, that could be right. Then, counting the horizontal lines but from the front, there's about 34 of them. That's a little better than just 8. Should be enough for everyone!
The manga is a shounen battle series, in which they're supporting characters. Opinions on the story's quality aside, you're not going to be getting much yuri