Just how many people are required to run twitter? Probably a tiny fraction of the number that was there.
Depends on what exactly you mean by "run Twitter". Keep the site operational so folks can Tweet and see other tweets, or shape a worldwide societal narrative.
Real engineers versus "social engineers". I'm sure he'll find plenty of skilled engineers that want to make a boatload of money and don't care about working 40-50 hours a week because they're doing that anyway at their current job.
See above.
I think that's the real cause of all the Twitter [ex]employee, and liberal twitter user angst. It's not that these social engineers weren't doing anything between there rounds of meditation, massage, and Kambucha. It's that they WERE doing something they thought was important, and now they are told it's not important, and their work will be undone. And to top it off, they can't say what they were really doing that has them so wound up, because they spent a decade wink, wink, nudge, nudge saying they weren't doing it.
Personally I love to see unemployed collectivist social engineers as, like locusts, when they do labor they only destroy useful things. I have also been entertained spending the morning reading about the end of Twitter, on Twitter.
It remains to be seen how many of the folks at Twitter are going to be onboard with it's new direction, and whether Elon can find enough over-dedicated folks to run it. I think he's been successful at finding those folks to work at Tesla and SpaceX because he sells the companies to employees as transformative to humanity and doing important work. Folks are more willing to work crazy hard hours and sacrifice downtime if they think they are changing the world*. I don't know if Elon will be able to sell "Twitter 2.0" as the exciting, transformative, cutting edge place to be that attracts the type A personalities he wants to employ. I guess we'll see how he brands it and what he says he plans to do with it. SpaceX crashed a lot of rockets before they landed one. I'd expect to see a similar number of "crashed" ideas at Twitter before (if) they manage some paradigm shifting social media product.
*Ironically, last year's Twitter employees seem to be the exception to this. They thought they were shaping the world, but still weren't willing to work super hard.