Got mine yesterday too. Nice fit, but I'm not a big fan of how big it makes my phone now, and adding the headphone extender is crazy, because the idea was supposed to be not require any additional cables because the battery is part of the case! Now I have to carry around this headphone extender. And by the way, stock earpods do fit into that channel, but it is really a struggle to send the cable down that tunnel and get it to mate with the phone. I think you would be better served taking the lower section off, putting the audio jack into the tunnel, connecting it to your phone, and then connecting the lower section to the upper section.
As others have mentioned, the Micro USB connector only charges the battery, it does not sync. It's a shame, because Apple can make a Micro USB adapter that syncs and charges, but I think they are restricting OEMs from doing the same thing.