One of the aliens died? I don't recall that.
At the end when Banks talks directly to Costello "behind the screen", she asks about Abbott and is told "Abbott is death process".
"So I've got bullets, but no gun. That's quite Zen."

No one of the two was dying. They didn't state that he did in fact died, but probably did Sad.
War, what is it good for?

One of the aliens died? I don't recall that.
I highly doubt those octopus are the alien's actual bodies. Most like some form of tissue bots controlled by aliens far away from earth. Or perhaps they are just AI's.

Well the aliens couldn't be projecting their images. Remember, one of the aliens died from a beep load of C4 explosives. Maybe they were teleporting there, they had such huge spacecrafts. The only thing unknown is: were all the different countries talking to different aliens?
The spacecraft are supposedly vessels to travel through space. In the film, I assume the ships suddenly appeared out of nowhere. Then at the end, the ships dissolved away.
I'm thinking the ships were phasing in and out from another dimension, hmmm?

Interesting theories. I had not thought of that.
Schrodinger's cat walks into a bar and doesn't.

Cool idea. I like the teleport to the meeting location. Then the egg is an intercom and not a ship.