Just read the Leia card from the Tantive expansion.

I don't have adrenaline rush with me here at work to compare the wording. But on Leia it states that you may treat all red maneuvers as white when you reveal them until the end of the phase.

Does that mean that you can discard Leia and have ships with stress on them, give them red maneuvers and those maneuvers counts as white when you reveal them? It looks that way to me, but several people I have heard say that it is just a more expensive adrenaline rush. Am I wrong or are they wrong?

You are right, Leia's card means precisely that. And by the way, that's also how adrenaline rush works too.

If you select a red manuever for a ship with a stress token, you can discard 'Adrenaline rush' to treat it as a white (and thus, legal) manuever. So, you could perform it without your opponent choosing a non-red manuever for you in the dial.

Leia is, in fact, a massive version of 'Adrenaline rush'.

Yes, it does work that way. Adrenaline rush for the entire fleet.

One minor detail: Both players assign maneuver dials first. You declare and discard Leia after that.