...could you please rank those methods from the most preferred and supported to the least recommended and suppored?
They are all equally supported as far as Telerik is concerned. "Preferred"? That's honestly hard to say. Generally it comes down to what architecture you'd like to use in the end and your personal coding preferences. If you're big on Microsoft tools, I might try the MSTest approach. But that forces a dependency on Microsoft tools for your architecture. Alternatively you could use our own runner and remove that dependency. If you like the idea of creating your own desktop application for managing/running tests, I'd probably go with RunHelper.Test. Does that help any?
Do I need a separate license to run tests through ArtOfTest.WebAii.Design.Execution.RunHelper.Test ?
Nope. You'll need a minimum of one full Test Studio license in order to record and design your tests. Then one Run-Time edition for each machine that will be executing the Test Studio tests. Nothing special to use RunHelper.Test as it's built into the API for both licenses.
Now is there a way to convey the results from my custom test running application to the "root" test studio, so that it sees my test runner as a coded test ?
Since RunHelper.Test returns a Results object, that's pretty easy for the local machine. The hard part is gathering the results from the remote machine. If the remote machine runs the test via our ArtOfTest.Runner you could use the Out and Result command line parameters to create the output result file (.aiiresult file) on some network share with a static name, then let the local machine pick up that file, parse it and incorporate it into the main tests results.
the Telerik team