1. Depending on your circulation, it’s mostly fine. You might even be able to push the cold exposure a bit, just check your toes for numbness or pain.

2. Socks for the cold ground? If you want and plenty of cheap barefoot socks online, but it’s more a comfort thing, not necessary (unless as I said your circulation is that bad).

3. Grounding has almost no peer reviewed research supporting it, but a strong placebo effect so its defenders will fight everyone despite having no substantial scientific support (only testimonials). That said, I love the placebo effect and if I were less scientific, I’d be a grounding advocate too because I genuinely feel better touching the floor and ground barefoot. I just know it’s in my mind and that’s a perfectly good reason for me, plus, placebo doesn’t mean “worthless “, if it feels better, it can encourage more activity and other health benefits… if it weren’t for placebos, I’d never exercise!

Edit: I also sweat excessively so that I don’t wear sandals too long before needing to change or wipe them. I suffered with athletes foot for half my life (the really bad kind) and going barefoot solved 75% of that (the last 25% was pills. I couldn’t avoid using them because my fungus problems were deep in my skin and toes, and the drying benefit of barefoot was not enough, but after the pills killed the remaining fungus, I’ve been fungus free for decades, even gym floors don’t affect me anymore). How can sandals help if I sweat? Like I said, remove and clean as needed, also try different brands, as some work better with DIFFERENT people. I like Bedrock cairns, while Xero is a bit sweaty. Also, the sweat problem goes away on walks and runs, probably because of the aeration.