Hi Namrata,
Hope you got your second issue resolved.
For your first issue, i.e. unit of measurement is not getting captured for same plant/dist. channel/division.
In SAP you can create multiple number of materials with the same plant/dist. channel/division code combination.
In your case first decide what is the "Base unit of Measurement" of that trading material, then search(or press F4) to view the list of base unit maintained for your organisation and select the required base unit of measurement for the material. And after this other fields also get activated for making further entries.