It's sad that no one has commented yet so...
1. I really like this one, I think it's your best here. The nose is a little creepy though, and I can't tell if it's a guy or a girl. (It looked like a guy to me but the more I stare at it...maybe it's just because I'm tired...)
2. Yeah, the mouth needs help. I'm not sure how to explain this but...in manga, when the mouth is open from the side, you drop the lower jaw down a bit just slightly. You draw the lips like you would when they're closed (an elongated "m" shape) but just stretch it a litte. Then you draw in the mouth. Depending on the angle you might be able to see the upper and/or bottom teeth-row-thing. Make sure to leave a little section of "skin" between the edge of the mouth and the lips.
(Of course it changes when they're screaming or something....open the mouth up, draw just and edge of the top teeth, and draw the far side of the mouth---like a backwards "c.")
3. It's...okay. His eyebrow is uneven and his hair is just plain strange.