Yes, Comio S1 does have the front camera LED flash.
No. Comio S1 does not have dual rear camera. It has single lens camera with 13MP resolution.
No. Comio S1 does not have the removable battery.
Comio S1 does have a very decent battery back up. It has 2700 mAh Li-Polymer non-removable battery which offers almost 15 hours of talk time and up to 143 hours of stand by period.