Make queries and BCP faster on a very large table
This is a long shot but seen as you are running SQL 2014 Enterprise I would have a test with using a Clustered Columnstore Index on this table and see if this improves performance for you.

Especially considering that you are using the table for selects and bulk inserts only - no updates and no deletes.

You will have the added advantage of taking a bit of load off the spinning disks and moving it more towards the CPU / Memory which you seem to have a decent amount of.