Also, I saw that you seem to endorse the original RKC book for kettlebells. I got a 16 kg bell, and some extra money, was thinking of buying a 20, 24, 28, 32 kg. Is it too much? Are 8kg jumps (24 and 32kg bells only) better?
Welcome, Julien. On rucking, I’m no authority, just an enthusiast. But I’ll pass along the good advice I got when starting out:
Start with 30lbs./14kg or less. With more than that, you can irritate your knees. If you need more load, wear ankle weights. According to Army researchers, you expend as much energy to move a pound on your foot as you do to carry five pounds in your pack.
Speaking of feet and knees, take good care of yours. If something hurts and gives you knee tendonitis, stop and change insoles and shoes/boots til you find the combination that doesn’t. (Spenco green insoles have a lot of fans and they’re reasonably priced. And I’ve become a big fan of jackboots.)
For gear, I find the reviews on Varusteleka very reliable. If people there all say it’s a great pack, it’s a great pack.
Nevertheless, individual build counts for something. E.g. if you have narrower shoulders than most, a given pack will fit you differently. Happily, surplus is cheap so you can afford to experiment.
For rucking, my personal guru is your countryman Sgt. Šileika of the Black Watch, who says, “strap padding means nothing, strap width is everything.” (Or words to that effect.) As always, the leathery old dog of war speaks in nuggets of golden wisdom. My favorite packs have turned out to be the ones with wide leather straps.
My starter pack remains one of my favorites for short, heavy hauls: a Czech M60 that cost $5 that I upgraded by spending another $10 to buy leather straps (actually suspenders) on eBay from a guy in Latvia.
On kettlebells, I have more of a right to an opinion, and I have a firm opinion on that question you asked. I’ll return to that tomorrow.