Yes, Gionee A1 Lite does support OTG.
Gionee A1 Lite has a metal Alluminimum Alloy body.
Yes, Gionee A1 Lite is a true 4G VoLTE mobile phone.
No. During our review did not find any major heating issue. However, since the mobile phone is made of Alluminimum Alloy body and has got huge 4000 mAh battery - you may notice some heating issue while charging.