As far a number 1 goes, I experienced wrist pain the most consistently when I was using a curved ergonomic keyboard. Based on my personal experience, curved keyboards aren't the best route for everyone.
However, good point about Vim - cutting down on the need to switch from keyboard to mouse and back also seems to help with my wrists.
Another advantage of Vim is that it lightens the load on little fingers. You don't need to press Ctrl or Alt very often. Compare with Ctrl-N, Ctrl-P, Ctrl-F, Ctrl-B on Emacs...
However, good point about Vim - cutting down on the need to switch from keyboard to mouse and back also seems to help with my wrists.