Yes, Moto C has removable battery.
No. Motorola Moto C is made of solid Polycarbonate material.
Yes, you can. But right now back panels are not available in stock, since the model is just launched.
No. You can use only one sim card on 4G mode in this phone. You need to use 4G sim card in sim card slot one. Second slot shall use 2G sim card.