So was the gameplay trailer what it will look like or was it not polished

A bit of both.
On one hand, the trailer says it was filmed in-engine and is representative of the game.
On the other, Bioware says they'll keep polishing it until release.

They'll be polishing it.

Ah thank you for remding me of the amazing gorgeousness that Cassandra became. 

It's all representative of the game running on a PS4 and zero visual trickery or CGI "representative of game experience" crap... but it's unpolished so the final product will probably have better visuals, hopefully better face animations and I hope the lighting will be improved too. It looked worse than Inquisition graphically in the free-roam areas, where the Nomad looks like it's made of plastic. It seemed a bit like the current optimization had the game at medium settings on PS4 or something.

^ Hey, dude, speaking of Cassandra and her loveliness, I hope more of this but with blue butts and stuff

That to me was both mature and tastefully done and also reminded me a bit of GoT when it doesn't go too overboard. I think showing naked characters is cool, especially your protagonist lol, and it's not in that Witcher exhibitionist sexist way where it zooms in on the ass... except... well, Dorian.

About the music.
I noticed at 3 minutes we hear excerpts from Project Overlord .
But the rest is new to me.

However none of the ME3 trailers used genuine sound tracks from the game except the one released on March 2nd , 4 days prior to official launch
in which we hear the Clint Mansell main theme.

So i wonder if the first theme here will appear in the game .
The OVerlord bit is during real gameplay so i gather it will be there?

Has there been anything released on Twitter or elsewhere about the music ?
I find it's an important element... music always is

input ?