Why did Shinji choke Asuka at the end?

Shinji chokes Asuka to test his agency in the new world he’s created. We’ve gone down the deep, deep rabbit hole that is “Neon Genesis Evangelion” theories, and the most concrete thing we’ve been able to find is a single, very suspect translation from a card game.

Why did Asuka come back to life?

Asuka survived because everyone was able to come back, not just Asuka. Rei explained that everyone, who wants to be a individual again, can become human again.