No. Tecno Camon iAce does not have the fingerprint scanner.
Tecno Camon iAce comes with 5V / 1.2A output charger in the box. It does not support fast charging like 2A output charger but the phone definitely charges faster when you use the original charger.
No. Tecno Camon iAce does not have the face unlock.
Yes, Tecno Camon iAce does have the front camera LED flash.