3. I got to a speed of about 70 wpm in about a month practice, but then, progress stagnated. I realized that if I wanted to be as good in Colemak as I had been in qwerty, it would mean putting in the same amount if not more of work, since at that point, it wasn't a question of quick fingers or memorizing keys, but memorizing whole words as a movement-sequence. That was pretty demotivational.
4. In Colemak, the right hand has slightly more work than the left. It's the other way around in qwerty, which favors the left hand very strongly. I found that my left hand was quicker and more agile than my right, although I'm right-handed, and Colemak's emphasize on the right hand made my typing feel awkward and sluggish. I attest that left-hand ability to decades of playing the e-guitar, but that is just a hypothesis.