1) In the preferences you can set your PL/SQL compilation settings. I've written about that here
2) Not sure what the requirement is here, can you provide more information?
3) You may be onto something with the data modeler. It allows for Data Flow Diagrams, but I'm not sure that's what your customer is looking for. An example might help getting us in the right direction.
4) No. But if you frequently save your work, SQL Developer does auto-reopen documents that were left open when the application closes. And in addition we provide built-in file history/change management.
Clarification requested by you for Qn # 2.
here is what the Customer had to say
In point 2, I wish to know how can we highlight other schema objects used in the current schema. For example, In a query, if I am referring to a table which was created in some other schema, the table referenced should be highlighted in a different color or font. Is there any way I can achive this? I do not see any option in the preferences tab.
No, we don't currently support that.
Thanks a lot Jeff.