The URL you tried should work. Many discussion around at [1].  If AEM 5.6 make sure the fix [2] is installed. [1]    http://forums.adobe.com/message/4652639#4652639#4652639[2]   http://helpx.adobe.com/experience-manager/kb/56-rte-plugins-disable.html

IIRC you need custom implement following damadmin Or siteadmin. There by adding own servlet etc...  Unfortunately Not available out of the box. Please file a daycare to file enhancement request.

You should look at xtype widget you are using & document has all the details.  In your example using selection widget so details at  http://dev.day.com/docs/en/cq/current/widgets-api/index.html?class=CQ.form.SelectionIn fact you can use any arbitrary name does not matter as long as inside the implem...

http://dev.day.com/content/ddc/blog/2010/05/you_do_not_have_toc.html

You are listening to replucation event & durbo is already created & you might not see the latest property changes if you do any.  What is your exact use case.

Documentation request has been placed to update. For now use like [1] & also make sure to have else block in your code to return default value for unhandled case.[1]   return new Packages.java.lang.String("user-a")

No idea. Can you file daycare & in the ticket upload 10 thread dumps at 2 second interval after stop is initiated. 

If it is not a cluster environment comment out <Cluster> ...</Cluster> param in repository.xml then restart the system

follow http://helpx.stage.adobe.com/experience-manager/kb/startup-failure.html

One sample filter for a reference at  http://aemfaq.blogspot.com/2013/05/blocking-anonymous-access-to-crx-in-non.html