Not really. The UK uses imperial units for most of the things you use units for in daily life (roads, cooking, drink sizes, body weight, utilities, land area...), even though they theoretically converted to metric. Canada is similar.
Not really. Old people might cook with funny old temperatures/measures and weigh themselves in stones, but it's fading out, contemporary cookbooks and gym culture are all metric. I've literally never seen a utility bill in anything other than metric (even if it's slightly weird metric like kWh or cubic metres of gas).
Kilograms seem more and more common for human weight too though, largely driven by fitness apps & communities I think. I doubt children in school today are accustomed to stone; only pounds and ounces for birth weight perhaps, but even that is metric medically and converted for the parents' familiarity these days I believe.
Fraid not.
No medical professional in Blighty weighs people using imperial measurements. The only people who really use them are the elderly and (bizarrely) the type of crappy slimming magazine seen at supermarket chekouts...... The kind satirised by Viz as titled "Less Cake, More Exercise".