Not sure about the first one. I work for a big company and when we hire we definitely human-read lots of resumes, which isn't to say that machine readable is not a plus. I agree that tailoring may not be worth it.
I'm surprised nobody mentions hobbies etc. Maybe I'm just an old fart but I like to get an idea of the person as well.
The main problem of hobbies is that I typically don't think they matter enough to deserve space on the single page of your resume. I'm not even a decade into my career and I'm already considering cutting my college stuff down to "COLLEGE NAME YEARS ATTENDED DEGREE GPA HONORS" in a single crammed line. I think I'd put down my in-major GPA and emphasis courses before I'd put down that I like video games and my cats (.....which let's be real, you can probably just assume is in the hobbies for software engineers).
It'd depend on the field (and region), I imagine, but after the first job or two I feel like all that matters with respect to schooling is that you went. Five or ten years into a career I'd be surprised if coursework that hadn't been used on the job was relevant, and GPA wouldn't even be considered.
Hobbies are probably not that useful either, but I could see them catching a hiring manager's eye. Coursework probably won't have the same effect, although I suppose it could help you get through ATS.
Not that I think anyone's really looked at my resume for over 20 years (jobs through network), but I think the idea of a hobbies line is that it can be a conversation ice-breaker. That said, I don't think I have one on mine. If theey Google me they'll turn up more than enough to talk about.
It varies significantly, as these things do. My first job out of college ~didn't accept people with below a 3.8, so they'd explicitly ask if you left it off (or worse, would assume it was <3.8 if you didn't bother to add it).
I'm surprised nobody mentions hobbies etc. Maybe I'm just an old fart but I like to get an idea of the person as well.