I think the initial attack was for resources (like a massive amount of relatively clean liquid water). Due to their technical superiority I don't think it normally cost them much to find and/or defeat planets this way. Until us.
Well....
salty water.
And to make your own water, just get some hydrogen and oxygen and apply heat. The hydrogen burns and you get (mostly) water. Seems like it'd be easier to do that than go after a planet with an ornery race of primates.
Go to Europa at Jupiter. Lots of water there, potentially a few times more than Earth has. Getting it out of Jupiter's gravity well might be difficult, but I'd imagine that'd be cheaper than a full military strike force.
Or check out Enceladus at Saturn.
This second attack I think is more of an "oh sh*t!" moment where they have lost an entire attack force and their tech is now in the hands of a species likely capable of using it. Lets see if we can wipe them out before they come looking for us, and if we can recoup some natural resources too that would be swell.
But now you're into another accounting problem: Sunk cost. They already lost an entire resource acquisition fleet, and now the resistance against a second wave is going to be even greater.
Maybe they have stupid bureaucrats too.
"No, we can't appear weak against lesser life forms. Keep pressing forward. I'll authorize whatever funding you need to get this done."
I dont think there was any loss of translation. He was shown images of this almost unimaginable large attack force moving from planet to planet and striping them of everything useful. One could easily assume this is an entire civilization moving itself place to place. Or he could have easily seen several such attack groups doing this while realizing it was their entire civilization.
Could've also been a memory of something the alien saw in a propaganda film, or a really moving Youtube clip.
Based on the sheer size of the craft crashing, and the relatively intact nature of it, I wouldn't be surprised if some aliens did get out (and the website linked here says some did escape).
It
is a darn large crumple zone, at least for the aliens with offices in the top floors.
As far as adapting the tech goes, it was the aliens who first adapted their tech to ours. They thought it would be clever to utilize our own satellites since they were there...that created the back door that let us into their source code or what have you. It's not like we immediately knew how to use their stuff either, just how to break it. It takes 20 years for us to have adapted the tech to the point in this new movie.
Also an odd choice, like us choosing to use cave paintings to coordinate an attack.
In the real world we already have lasers and rail guns and plasma tech. Our problem is more of a power issue. If we could utilize just the alien power tech we could create some crazy "sci-fi" weapons. Utilizing any of their other tech to advance these designs could make them seem alien.
Hopefully they have something that's better than lithium-ion batteries: Something to allow a smartphone that lasts a week without recharging.
(Gotta prioritize what we're going to do this new technology, right?)
omgomgomg is it michael bay? it's got to be michael bay. please say it's michael bay. i wanna see stuff go boom.
Don't forget the copious product placement. The movie will have a net cost of -$75M, making money before it even gets a single viewer.