RE: [1] this is somewhat dated but a “contractor” friend used this “twenty factor” list to determine her “employer” was acting questionably maybe ten years ago: https://www.lakeshoreacct.com/blog/what-irs-20-factor-test

The site says the IRS no longer uses it but it’s still generally a good rule of thumb. And yes I recognize the irony that both her and her employer used the terms contractor and employer when describing their relationship.