Can you share more details on the issue? Like, which feature (Data Feeds/ Data Warehouse) you are using and exactly when you are seeing the error?

here is no way to save drop downs. However, you may create save a sample template and reuse it in new Workspace projects.

Please open a ticket with Customer Care team with the details so that it can be added to the device look up, if not added already.  

To answer how to check Campaign is set everytime it is expected, you would need to check the server call sent to Adobe servers in the Network tab.

The API request you pasted, does not show correctly at my end. Perhaps, I have the font missing. Also, the request IDs can be checked by the Customer Care team as well as the debug logs. I would advise reaching to Customer Care team for help.

Do you have an example or live web site where this is happening?

 There is no ETA available ARB with 2.0 as it is still under development. It may not be released until next year.

There is no way to delete non compliant data real-time. However, you can use Data Privacy or Data Repair API to create and submit a deletion request on user's behalf. 

It will also help to validate if Campaign variable is being set every time. Also, if the visit is not breaking during the session.  

Unfortunately, uploading traffic summary data such as PV and Visits is not possible.