Bill, you're really raising three topics, which are indeed related but separately documented (to different degrees).
1) First, as for use of any CF license key for DR (or staging or test or central development), that is covered in the CF EULA (End User License agreement). I realize many regard reading a EULA as like getting their teeth pulled, but the CF EULA is really pretty straightforward and only several pages total, with just a few paragraphs on matters like "disaster recovery" (the term literally used in the EULA).
I have a blog post with info on how to find the CF EULA, either locally to you or online.
2) Then you ask whether you should expect a watermark on an instance running as DR. The answer is no. Only the Developer edition (what's referred to in the EULA as "developer edition software") has any watermark on the output of things like cfdocument. That said, I am not aware thet there's any doc that lists WHAT features might show such a watermark. (I can only imagine it to be PDF-related tags and functions.) But no, using a "real" license for DR, you will NOT see any watermark.
3) Finally, you ask questions about activation. That's a totally separate (though again, related) topic, and that's covered in detail here:
https://helpx.adobe.com/coldfusion/using/coldfusion-licensing-activation.html
Note carefully how that page first has several questions--which you must expand to see the answers, and then it ALSO has several pages worth of more info below that, including for example an entire section on deactivation, if that may be helpful.
4) To be clear, there is NOT currently a way to change the type of license in the CF Admin UI. I have filed a bug report for that. That should come in the future (and should not require a restart).
Even so, for now it IS possible to change the license type by modifying the underlying licenseinfo.properties file that this page modifies (not to be confused with the older and still existing license.properties file), both in the cfusion/lib folder. I discuss this more in another thread here.
While these things I share are quite "documentation", they show that searching this site (community.adobe.com) and the CF portal (coldfusion.adobe.com) can often help one find info that others have shared.
Again, we can help that Adobe will fix the deployment-type UI problem in the future. Add your vote to the tracker ticket. As I like to say, it's better to light one candle than to curse the darkness. And I hope I've turned on some overhead lights for your path here. 🙂