Yes, Gionee X1s does have the front camera selfie flash. The front camera has 16MP resolution and you can get excellent selfies even in dark conditions.
Yes, Gionee X1s does have the corning gorilla glass 3 protection.
No. Gionee X1s does not have the NFC support.
No. Gionee X1s does not have the hybrid sim slot. It has 2 dedicated sim card slots and 1 dedicated MicroSD card slot. You can use MicroSD card of up to 256GB with this phone.