Re: How many instructors teach Ukemi Waza?
Some dojo emphasize learning how to roll out of throws if at all possible and don't teach breakfalling until a pretty high level. I'm ambivalent about this myself, but it's what my school does so I'm trying to work with it. It has to be combined with a responsibility on nage's part not to force uke into a breakfall.
We spend a lot of time working on rolls, though. I have the impression that many dojo are satisfied with forward rolls when the student can do them safely, but my teachers hold out for round, quiet, and in a straight line as well. (My current challenge is, "When you can run across the dojo and do a round, quiet, straight, and unflinching forward roll, then I'll consider teaching you breakfalls." I have quite a way to go on this, I fear.)
Ki Society doesn't tend to give uke any more energy in his fall than the energy contributed by his attack, so it's easier to avoid forced breakfalls than it would be in a "harder" style. But I've failed to avoid a couple, fortunately with no bad results.