Can you Survive Underground if an extinction level meteor hits THE OTHER SIDE OF THE EARTH?

Yes, you could... it’s not that much different than being on board a submarine.  If you have a fuel source that can last months and years, the food you need, access to water, the ability to remove waste - you could survive...

But... would you want to?  That’s a big question - especially when you consider what kind of world would exist going forward...

Think of the earth as a large space ship. As long as the life support system continues to function, you’re ok. Otherwise, you're not.

Survive the initial impact? Yes. Survive long term? Not so sure. All infrastructure would be wiped out. Could you see millennials being able to survive without a cell phone permanently stuck up their ear?

It would depend on the size and velocity of the body in question.

i dont think so

Maybe if they made the right preparations. 

The direct opposite side of the earth from an impact would be a bad place to be, the shock would transmit through the earth like a giant lens and fry that spot.