Do the founders or originators of a meme coin have to disclose who they are and how much they own? Is there a holding period or can they sell day one? Do sellers have to file a form 4, form 144 or any type of filing to disclose who may be selling?

Probably not (not legal advice). The SEC used to strongly take the position that most crypto coins were securities, and that coin issuers and exchanges were breaking the securities laws by not registering them the way any other public stock would have to be registered. One reason why the crypto community loved Trump so much is that they expected him to rein in the SEC. So while most ordinary crypto probably is a security under existing precedent (representing a token of ownership that derives value from a common business enterprise), the SEC probably will not take that position any more.

But even under the old SEC approach, meme coins probably weren't securities - and thus didn't have to comply with securities regulations. Because....they're memes. There is no business. There is no common enterprise. They're associated with....nothing in the real world. They're not serving any functional purpose in any other context other than lolz. So they probably weren't securities four months ago, and they're very more probably not securities now (not legal advice).