That is they way that nodes work with multi-field. What is your issue with this functionality? 

Did you hard code the response code into JSON?

I am not sure this is support in AEM out of the box. That is - child pages rendering content based on parent page content.  Look like this may have to be a custom solution. 

See https://helpx.adobe.com/experience-manager/using/integrate-digital-marketing-solutions.html

That is an incomplete tutorial. If you want to do an end to end one- see this one: https://helpx.adobe.com/experience-manager/using/first-osgi.htmlAlso - there are many end to end AEM HELPX articles here: https://helpx.adobe.com/experience-manager/topics/how-to.html

This requirement would be done at the Java level. So in your Java proxy classes, ensure you have the correct application logic to consume the encrypted SOAP call. There is no configuration setting on the AEM side. All the logic has to be within Java app logic.  

CQ comes with a tool to help in these situations: http://cq-ops.tumblr.com/post/23543240500/how-to-use-cqs-query-debugger-tool

Do not use XPaths anymore. Use: Query query = builder.createQuery(PredicateGroup.create(map), session);

that documentation topic is the correct location to learn how to address your requirement. 

AEM does expose a Java API to get services: https://docs.adobe.com/docs/en/cq/5-6-1/javadoc/com/day/cq/wcm/webservicesupport/ConfigurationManager.htmlYou will have to see if this API does what you want.