To check the f/w version perform the following:
Run the Samsung SSD Magician > System Information > Drive Summary > Samsung SSD Pro Series
From here you will see all the information on the right hand side about the drive including the f/w. DXM04B0Q should be the latest.
As to the question
is installing the firmware absolutely necessary?
You should as the first batch of these drives were released with wonky f/w which caused some issues which were then later rectified with new f/w.