Thanks Joe and sorry for the delayed response. I thought I'd get notified of each new post to my threads, but that is not the case.
Yes, the contractor is licensed to do lead paint abatement.
I don't know if he's using HEPA filters on his vacuums, and if I ask, won't I be the customer who doesn't trust him?
Copper vs PEX plumbing - apparently, the building department explicitly forbids the use of PEX tubing so the plumber went with copper.