Is Micromax Bharat 3 is 4G mobile phone?

Yes, you can use Micromax Bharat 3 as a Wi-Fi hotspot, too. 

Yes, Micromax Bharat 3 does have the front camera LED flash. 

Yes, you can play HD videos on Micromax Bharat 3. 

Micromax Bharat 3 runs on Android 7.0 Nougat OS.