Building and digging with keyboard would be prohibitively hard - at least for me. I suggest keeping the most essential functions as these to the mouse.
By the way, I really like Sergey's idea, but I feel that the smooth way to do it, and the way that fits the theme of this whole idea is to allow each command a hotkey, but then hotkeys would be prohibitively long and confusing trying not to be the same.
But of course we could have a teleport function as part of the game separate from commands.