I have a new Creative Labs Sound BlasterZ sound card and just purchases the Plantronics Gamecon 780 USB 7.1 gamer headset.
I play Battlefield 4 primarily with headphones.

Now my questions are: 

1. Am I bypassing the sound card when I plug the USB headphones in?
2. Am I getting the surround sound from the processor in the headphones or the motherboard?
3. Would it be better to plug analog headphones into the sound card.
4. Can I use a USB to standard headphone jack adapter then run it through my soundcard. (how well would that work?)
5. Is the sound card just a waste of money when it comes to headphones.
6. What headphone and setup is going to yield me the best sound quality for Battlefield 4?