Yes, but only for the business directly owned. In the US, it's perfectly legal to run things through shell companies that make things much more difficult. E.g. instead of directly owning the company, he could put his share in fully-owned shell company, based in a country that doesn't report the owner.

Basically yes. There are a large number of public repositories of data that can dox a persons address. Like property tax rolls, company filings etc. some of these are actually required by Europe (https://developer.apple.com/help/app-store-connect/manage-co..., which I do not appreciate)

Land records are public in most US locales. You can type in almost any residential address on homes.com and it will show you who owned it when and with what loan terms.

Not really, it looks like this guy originally registered the business at his personal residence which is not really common. Kinda surprised if he still lives there considering how FLOCK has expanded.