Yes and their eyes "flash"-their eyebrows raise and their eyes brighten/widen when they see you but it is often very brief, like less than a second. Though I do notice that when certain men who flirt with me see me their whole face tends to "light up"-their eyes widen a bit and their eyebrows go a bit up and their entire face seems to open up with a friendly expression, this is the "eyebrow flash" and is probably easier to notice than dilated pupils
Yes. However, pupil dilation can also be cause by lighting and is a reaction to seeing someone with dilated pupils. Some people also have naturally large pupils, so its kinda hard to use pupil size as an sign of how someone feels. You have to know the persons baseline dilation, and you have to factor in lighting conditions.