Use the plugin here: getQueryParam | Adobe Analytics You would need to install the plugin in your Analytics setup. You can then set campaign from query param in document.referrer by using this code:s.campaign=s.getQueryParam('cid','',document.referrer); 

Yes you can use classification to resolve this.

There is no list available publicly. However, you can work with Customer Care executive to get those Search Engines validated.

You may use your existing report suite. However, I will advise trying it out on a dev suite before making any changes in the prod report suite. You do not need to create a new Launch property.

Unfortunately, I will not be able to suggest anything related to Google Data studio. You might try posting it in GA Forums.

If you are referring to Workspace for removing the grand total, you can d so by clicking on the gear icon in the metrics header.And then uncheck "Show grand total". 

Using a prop to set country value should work fine. You may also use evars with expiration of hits. The problem mostly people face using evars is when the expiration is set to visit an visitors change the country mid visit. I do not think using props will limit any reporting capabilities, except for...

Got it and thanks. Hope I was able to answer your query.

That is not a standard and solution divided is based on the business requirement. If you can share more details on your business case I can share my comments over the solution.

If you are just looking for Returning Visitors, you can use this segment. Let me know if that helps.