Yes, Gionee A1 Plus is a true 4G VoLTE mobile phone and you can use VoLTE without any problem.
Yes, Gionee A1 Plus does have the front camera LED flash.
No. Gionee A1 Plus video recording is restricted to 1080p resolution. You can record Full HD videos but you cannot record 4k videos.
Yes, Gionee A1 Plus has a 3.5 mm headphone jack.