Great advice! Thanks for sharing :)
A bunch of this definitely does generalize, especially:
“If you have multiple research ideas, considering writing more than one (i.e. tailored) SOP and submit the SOP which is most relevant to faculty at each university.”
“Look at groups’ pages to get a sense of the qualification distribution for successful applicants, this is a better way to calibrate where to apply than looking at rankings IMO. This is also a good way to calibrate how much experience you’re expected to have pre-PhD.”
And if you can pull this off, you’ll make an excellent impression: “For interviews, bringing up concrete ideas on next steps for a professor’s paper is probably very helpful.”
CS majors and any program that’s business relevant (e.g. Operations Research and Financial Engineering) have excellent earning/job prospects if they decide to leave partway through. I think the major hurdle to leaving partway through is psychological?