Looking for some confirmation/information on copyright law as it applies to artwork

Yes, generally you're right.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.

All works published anywhere in the world -- including in the US -- are in the public domain in the US. Paintings by Van Gogh are clearly in the public domain.

The duration of the copyright term of a work depends many factors. The chart at < http://bit.ly/1NpxbD > provides a very good -- and I think legally correct -- synopsis of how to figure out if a work is in the public domain in the US.

Wow. I left out a very important date in the first sentence in my previous response. The sentence should have read: " All works published anywhere in the world -- including in the US – during or after 1923 are in the public domain in the US.”

Sorry for the omission. The link that I provided to the copyright term chart makes clear that the 1923 date is the operative date when evaluating what's in the public domain.