Yeah, other wearable manufacturers who use the same display technology usually call it MIP instead. Pebble are pretty much the only ones who call it e-paper, which has led some to think theirs is a distinct thing, but it's just MIP.
Yes, or more precisely: reflective displays without backlight. There were many such display technologies a while ago (when the Kindle took off and various companies tried to compete with E Ink), but most have since been abandoned.
Pretty much all colored e-paper screens have much lower contrast than color printing on paper, since they mix colors by using can conventional RGB sub-pixels and darkening them individually, just like regular lit screens, which reduces the amount of reflected light.
Isn't that how color images printed paper works, too? We use inks (often in CMYK coloration, but a galaxy of other options exist) to subtract light from what would otherwise be reflected by a plain white paper.
What makes e-paper screens worse in this way?
No. When you print a piece of paper some color, e.g. red, it will be completely red. But most e-paper screens will only be 33% red (optimistically) and 66% black. This is because physical pixels usually can't change color themselves, only brightness, so you use three of them, and darken the RGB components, to produce a colored pixel.
For displaying white on color e-paper screens you will have three non-dark RGB sub-pixels, but each color component only reflects at most a third of the incoming spectrum, either red, green, or blue wavelengths, while white paper (or monochromatic e-paper screens) will reflect all three wavelengths everywhere.