Legacy data transfer

Hi experts,

In the course of transferring data from legacy system to SAP system--

1) we create the Excel file in a format that sap Understands ?

2) We save that file in the sap Directory using "CG3Z".

3) then access the file using "RHALTD00" for batch input.

my questions-

1)Please correct me if i am wrong or Anything needs to be done in above process?

2) while creating the format file for 5 "Positions" , do we have functionality in SAP, that gives the file with all the "header descriptions" ready to put in sap's directory Or we have to give this Structure manually in legacy system? as below-

(Ideally it should be present in SAP, just data to be filled by the client)

Thanks