will I get shot by friendly npcs or my companions if i stand in their line of fire?
or will this only happens in the hardcoe mode?

im not entirely sure, but i believe friendly fire is affected in hardcoe mode only since i have yet to play in hardcoe, ive seen friendly fire towards me from friendlies and companions do no damage to me.
im sure someone else who is more familiar with that issue will chime in though.

Friendly fire is in effect no matter the difficulty. Just try as best you can to avoid standing in front of friendlies and companions... and be careful because they LOVE to jump in front of your gun as you pull the trigger.

It happens in any mode :whistling: I couldn't tell you how many time Veronica has dropped a 40mm grenade on me - (you'd think I'd learn by now :facepalm: ) Also don't be surprised if you get jostled by a companion as you draw a bead on a target :down: