Yes, you can use 2 4G sim cards in Comio C2. But at any given time only one sim card will work on 4G network.
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%.
No. Since Comio C2 has 4000 mAh big battery and to avoid heating issues, company has used high quality Polycarbonate body.
Yes, you can use the 4G Jio sim card in Comio C2.
It takes about 4 hours to fully charge the Comio C2. That is because it has huge 4000 mAh battery. If you use any good quality fast charger - the charging time can reduce by almost 35%.