That clause doesn’t limit the scope to only members of Congress or laws they write. Supreme Court interpretation, 14th amendment, etc. have expanded that to government writ large.

Free speech protections generally extend to government employees, except in the scope of speech related to their official duties, to my understanding. It would be difficult to seriously argue a pride flag in someone’s office in the past meets that criteria of official duties. My faith in the courts to consistently hold that precedent is not high these days, however.

No, at least not in the US. It does not meet the legal definition of theft because (I believe) the property was initially acquired legally.

Otherwise, the police would be doing repo for things like delinquent car loans, which is dystopian corporate hellscape stuff.