No. Comio C2 does not have the fast charging support but you can use Sony CP-AD2 USB Charger to charge it faster. By using Sony CP-AD2 you can reduce the charging time by almost 35%.
Comio C2 comes with big 4000 mAh battery. It offers talk time of up to 20 hours and standby period of about 500 hours.
Yes, Comio C2 does have the front camera flash.
Yes, Comio C2 is a true 4G VoLTE mobile phone.