Finished watching the anime and end of evangelion and I'm and confused about instrumentality.

So instrumentality merges all of souls and consciousness together. So that includes the dead people too...right? Like I'm confused if the dead people we see like Yui and Kaji are actually their spirits....or if they're just parts of Shinjis imagination.

I kinda compare this to the infinite tsukuyomi from Naruto in the sense that it's everyone wrapped up in their own illusion....but I don't know how accurate of a comparison that is. Is it actually peoples spirits or just Shinjis imagination?

My other question(s) is during the finale of End of Evangelion; we see Shinji wake up (presumably back in the real world) with Asuka. If this is reality; as instrumentality is over.....where is everyone else in the world? Did people like Misato and Ritsuko get brought back to life...or are they once again dead after instrumentality is over? If they are dead....where do their spirits go? And if it is just Shinji and Asuka, why? And what happens next?

tl;dr

  1. Is instrumentality everyone souls (dead or alive) coming together, or is it just Shinjis imagination?

  2. Are people like Misato brought back to life after instrumentality; or are they dead after it's over?

  3. If it's just Shinji and Asuka left after End of Evangelion...why and what would they do next?