Ti Tharun,
(I) Implement an "on change" event on the text field. A commit of OEE and retrieve over association the Defects (change the name of the Entity to Defect according to the best practice). The association DefectImage_Defects
will give a list of images to the defect code. If you want the DefectImage to reflect the damage to an OEE the association should change.
(II) As you retrieve a list in your example this is not valid. The moment you are in a list view, all your requirements will work by default if you allow Mx StudioPro to fill the data view automatically
(III) You can retrieve the OEE list for a certain subset of the data. For example Machine_id (Using the best practice the attribute will not have underscores but something like MachineId) or Workorder. Change the type of the Rejection_Count to Integer and use toString($Count) when aggregating the list you selected. Then the new OEE you create can have the value $Count + 1
Go Make It