Could you check your network console in Firefox , are you seeing any error/blocks?  I have just tested with Firefox 106.2 with AEM 6.5.10, the visual composer works - Just FYI

One of the good blog to read through on this topic which answers some of your questions. https://www.opsinventor.com/on-choosing-a-disaster-recovery-strategy-for-adobe-experience-manager/  

It works on append mode only, deletion is only for Users, Service Users, and Groups.

"RepoInit operations are always additive, except for a few cases which allow removal of Users, Service Users, and Groups. Explicit permissions are not needed to run the RepoInit scripts. They have implicit permissions to perform all actions defined per the scripts."   https://www.bounteous.com/insig...

I just tested the Tags to CSV Exporter, i was able to download more than 3 levels. You can write query in debugger to pull the tags with date range properties and see. You will get the results in json but can be converted to csv in online tools.   daterange : This predicate is used to search a date ...

Can you try to set saml_request_path cookie with the landing page when the login is clicked and see?     

Well i don't have knowledge about how content exist in Oracle. But below are steps can be done to migrate and in very high level.   1. Extraction – Legacy systems may export content in flat file structures like CSV, XML, etc. In this step, the content is extracted from the source system before furth...

It's the factory configuration so it can be multiple. But does both have the same name which are being referred in the External Login Module? If yes, delete one from it and see ?  Also check whether you have config in codebase which creates this instance of config every time you deploy.

I feel this could be the issue/behavior with firefox not with AEM. Does a click inside the dialog make it disappear before you scroll down? 

What exactly is happening? Not seeing the values in the JCR after hitting save? Do you see error in browser console or you see a POST happening in networks tab?