They're working on color e-ink, I believe there are some color cholesteric LCDs sort of in production .... There are some discussions of them buried around MR, if you want more detail.
I saw somewhere (a couple of years ago) data on what adding a touch screen to e-ink would do to its viewable angle, which suggests that a touch screen can be added to e-ink. I think some of the ChLCD stuff has touch screens, but again, I can't point to details off the top of my head.
For OLEDs, I think their power draw will be higher than e-ink (since they can't turn off between page changes
), but they're s'posed to be
much lower power drawing than any other non-bistable type of display, as I recall.