How to create a custom form widget with experience builder developer edition 1.9

[WardahRashid]

I'm trying to create a custom form widget with ArcGIS experience builder developer edition 1.9 using ArcGIS JavaScript APIs. Custom form will take information from user input and update fields in one of the feature layer in AGOL. But, I'm having difficultly in accessing properties of feature layer in my code even after Importing all the necessary references 

here are some quick concern,

1- what is the elegant way to create custom form widget

2- If ArcGIS JavaScript APIs  can be used in Experience builder development

3- is there any example of that kind of custom form widget

4- how to access feature layer  and apply edits in experience builder custom form widget