I would not recommend relying on your own research or certainly on your own knowledge of trademark law to respond. In short, you can either revert to your old company name or hire a lawyer to protect your investment in your new branding. That should be a trademark expert. This is no more do it yourself territory than a persistent toothache.
I am sorry to say this, but this forum is not a substitute for engaing a lawyer. It is like attending a lecture with Q and A afetrward. So, we do not "verify" things like this.
The two songs from the 19th c. are almost ceratinly PD--I cannot think of how not.
La Bamba strikes me as 1950s first publication, but that is just when I first heard it. And that decade is troublesome, because of changes Congress has made in copr. duration. I am attaching a link to a lengthy table of durations....
It is not possible to answer, since it is not clear what ownership is meant. A trademark? Registered? Something unique to Texas? What made it ten years? Generally a brand as seems to be described cannot be used at all after usage stops--it is viewed as abandoned.
Perhaps the best would be for the asker to chat with a trademark attorney, many of whom will chat for 30 or 45 minutes without charge.
The short answer is do not tell anyone about it. If you must, for financing or joint development, first get the person to assign an NDA, a non-disclosure agreement. Of course once it is live it is exposed. The laws of copyright and trademark do not protect ideas. Copyright can protect the look and feel of a website to an extent.
The best protection is to get to market first and with a well-thought and well developed product whcih you then sell to the public with good marketing.
Using the circle-R symbol, while it may not be acted on directly by the PTO, may count against its unregistered perpetrator when someone else applies to use the same trade name. But this is all very fact and history intensive. The trademark law does not act like a tax code, so have a chat with a trademark attorney confidentially about all that is going on.
If you simply mail someone a check you will probably not get a release that protects you. It is possible this is a scam; there are some. And it would take some back and forth with the supposed Copr. owner to verify they own something you downloaded.
The short of it is you need a lawyer with some experience in the “download” area to negotiate for you, after interviewing you to get all the facts. I have experience, as do other lawyers on this forum. It will end up costing a good deal...
Being that you are five years post-registration, there are two forms you may want to file with the USPTO. One is a “section 8 affidavit,” that states you are continuing to us the mark and are thus entitled to renewal. You must file between fifth and sixth anniversaries of registration or lose it. The other is a “section 15” affidavit that asserts under oath that your use in a specified class has been continuous for five years. It gives you “incontestability” except under a few narrow...
I agree with Mr. Ratozza. If people are using your words, and you did not sign them over to the magazine 20 years ago, you would have two remedies, but both requiring the poem first be registered with the Copyright Office. One is to sue for infringement, in which case the remedy will likely be an injunction. The other is a “DMCA takedown complaint” to the host of whatever website has the poem, or songs containing the poem, etc.