I am why this should happen. API is supposed to work for the SOM provided. Can you please share the collateral and the script you are trying. Also what release of AEM Forms are you on ? 

Both of the releases are compatiable to each other.  There is a more easy way to write expressions that has come up with 6.1 FP1 . Rule editor is the new way to write expression with. Please have a look at https://helpx.adobe.com/aem-forms/6-1/rule-editor.html  

This is no provision to register any new AF component against any of the element/attribute type right now.

Yes you can achieve this by simply do it by dragging dropping you custom component from side kick and then giving correct bindRef (for putting bindRef -  open the edit dialog of the component , navigate to the script tab) to the component just dropped.bindRef for element/attribute can be seen by dou...

Session userSession = slingRequest.getResourceResolver().adaptTo(Session.class);String userId =  userSession.getUserID();You can do many othre things  like getting userManager , authorizable etc once you have the session.You can set a flag in JS and based on that flag write visibility expression on ...

Let me ask a few basic questions first. Are you able to access you page when you hit the apache port ?If you are not using dispacher but trying a web server (apache in your case). This looks to me a very common configuration problem. Can you try the first few links mentioned in  https://www.google.c...

Are you trying something like https://helpx.adobe.com/experience-manager/using/creating-aem-multifield-components.html ?

Please follow https://helpx.adobe.com/aem-forms/6/custom-submit-action-form.html  

I can say for sure that it would work with LC. For achieving the same via AEM workflow, you would need to write a lot of custom code. My re-commendation is to go with LC. 

Did you create follow the section  "Creating Cloud Service Framework" below from the doc https://helpx.adobe.com/aem-forms/6/configure-analytics-adaptive-forms.html