8. Does the X3MKIII support in-line remote control from headphones?

A: Yes. Please go to "System settings" -> "Supports in-line headphone control", and set it ON.
1. Volume control: Compatible with CTIA standard headphones for Android (plus some non-official headphones for Apple).       
2. Play pause/Skip/Fast forward/Fast rewind: Compatible with CTIA standard headphones.