Hi,
Once the Vendor is replicated to ECC, Vendor management team in ECC has to update the details and run the transaction code BD14, with the reduced Zmessage type,
Once this is transferred you will get a success message in Idoc.
Then this supplier will be available in ROS Purchaser view.
2) You can check the table BUT000 for the ROS Supplier.
Hope this helps you.
Thank you,
Anil