I'm mostly sorry for you that you're buying things to do cardio before giving kettlebells a proper go. Swings done right are so effective that jumping rope, even at high intensity, is something you do for warmup, or to keep warm between sets of swings. Once that gets easy, do Snatches, once those get easy, double kettlebell long cycle has you covered (and by covered I mean winded and miserable).
The beginning of Enter the Kettlebell is very nice. You're doing small concentrated sessions of turkish getups and swings. You're most likely going to start out fine and after a few weeks you'll do just great. For the next long while, you will most likely find a LOT of stuff to get better at regarding swings and form in general. Going to heavier kettlebells reveal a lot of small inaccuracies in your technique that you didn't notice so personally I've had a lot of benefit from doing a few workouts with a heavier bell from time to time, just to go back to my working weight and apply my new biomechanical experiences there.
The unwiedlyness (imadeaword) of non-competetion kettlebells means that, opposed to barbells, the movement mechanics are SLIGHTLY different depending on the bell weight, but it's different enough to make a difference when you're working with them.
I tried doing presses with an 8kg and a 16kg in the same hand to compare how it feels to a single 24 kg bell, it's really something and it means that I can tinker with my exercise for a VERY long time with the bells me and the GF own between us. 8, 12, 16, 20, and 24.
I'm genuinely surprised how much fun I'm having noodling around with kettlebells.
I think I love kettlebells. Sorry barbells...
So time getting into the swing of things: very little. Is there room to grow? Yes, definitely!