Yeah, it is much less stress on the knees to spin at a high cadence. I practice this in the winter on the trainer and keep it between 90 and 105. I'd suggest no less than 75-80. I picked up a wired bike computer with cadence on clearance for $15 this fall just for my bike on the trainer.

I've only fallen once because of the clipless pedals. I was on the lake for the ice races and started to tip over and I was about half way down before I realize I wasn't going to get unclipped! It does take some practice and I recommend riding for a bit and adjusting your cleats if you feel any discomfort.

And this is THE most important thing: Check the bolts holding in your cleats! If they get loose and back out, you might lose the cleat or not be able to unclip. I had to ride 10 miles home a few weeks ago when I lost both screws! I found the cleat which would have cost me $18 but the screws were gone. What a pain!