Brother, my advice ... Don't bother
I got heavily into KB's a few years back .... As did some of my friends. I'm the only one who didn't need shoulder surgery, but my shoulders were jacked for a long time.
Upper body deteriorated to shit, but my ass got bigger (nice look) .....and I was good at them to - 230 reps with a 53 in 10 minutes in the "SS snatch test" (google if unfamiliar)
KB's are a great conditioning tool or "finisher" .... But not something I'd base my routine around - and definitely not worth the cost of the various certifications, unless you are looking to make money teaching KB classes
Some high reps swings are all you need for cardio after your workout .... Centering your workouts around them will ultimately be disappointing, IMO