How to get proper results for these queries?

[Java Dev]

How to get proper results for these queries?

1. Need to execute and return 1st order detail alone for each order. Below doesn't work

https://services.odata.org/Experimental/Northwind/Northwind.svc/Customers?$expand=Orders($expand=Order_Details;$top=1)

2. Need to filter records based on order id. Below doesn't work and throws "Term 'Orders($expand=Order_Details)$filter=OrderID eq '10643'' is not valid in a $select or $expand expression"

https://services.odata.org/Experimental/Northwind/Northwind.svc/Customers?$expand=Orders($expand=Order_Details)$filter=OrderID eq '10643'

3. Invalid but returned results

https://services.odata.org/Experimental/Northwind/Northwind.svc/Regions?expand=Order_Details https://services.odata.org/Experimental/Northwind/Northwind.svc/Regions?expand=Territories

4. Not Returning Childrens

https://services.odata.org/Experimental/Northwind/Northwind.svc/Products?&expand=Suppliers https://services.odata.org/Experimental/Northwind/Northwind.svc/Regions?&expand=Territories