Jack-
By no means do I have the answers to your questions, because I have the same question.
However I can provide you what I've figured out so far-
My first grow was 3 Northern Lights and 1 Mazar. I used CFLs and a t-5 flourescent to veg and flower them. 2 of the NL plants developed 2 colas, one NL plant developed 2.5ish colas, and the mazar developed four. I handed the mazar off to a friend to take care off, and never got to see it finish because he fucked it up, but I know that after 4 weeks veg it had 4 tall even branches.
Next grow was 4 of the same NL strain (from marijuana-seeds.nl). This time, 3 plants developed 2 strong colas, and one plant (due to me accidentally topping one of the leading branches when making the Ben cut) just turned into a bush with 3 dominant colas. I used a shit-ton more CFLs that grow.
Now, I've switched to an HPS and am growing Barney's LSD and g13s WW. All four plants have reacted fantastic to the cut, and each has 4 colas up and running well (except for one of my LSDs, on which I literally DROPPED my HPS and lost a branch
).
So my guess is that the reliability of all 4 colas developing evenly is dependent on the genetics of the strain. However I'd also be willing to say that if you don't have enough light, or if CFLs are keeping light coverage uneven, you're going to see some branches outgrow others.