1. Eric, you are correct that the Update Rings policy doesn't know which devices are eligible, so the recommended way to use that setting is to set it to Update to Windows 11 until you get the eligible devices on Windows 11, then set it back to the off setting so that the feature update deferrals continues to work. Even better, is to use Feature update policies for the update. I'm not 100% sure of the AutoPatch plans for this, but I believe they will be moving the feature update management at some point.

2. We are generally recommending the update readiness and compatibility reports in Intune for most customers because it provides additional information like potential app or driver compatibility issues, in addition to the driver settings.  That does require enabling Windows data, which the Work From Anywhere reports in Endpoint Analytics do not.  In the end, as Aria pointed, use the report that works best for you with these considerations.

4. Your notion makes sense, so it depends on each report, since the reports for Windows Updates to include device IDs for that reason.  I can pass it along to our reporting team.