The movie files are Bink files that take a free video program to play. Google Bink and it should come right up for download. Once you have it, you can rightclick on a file and select open with Bink to play it.

Those do not appear in the tech tree file, anywhere. Unlocked components and improvements are affixed to the tech "bricks" by the improvement and component files. The models are pulled from where they are defined in those files.

I am not entirely sure of this myself. I know that the higher it is, the more likely the AI is to research the tech. However, I have no idea whether or not the actual value is important or just how big it is compared to the other AI values, whether the AI uses this to weigh things in trades, or whether the AI automatically values bonuses and unlockables or if those have to be estimated into the AI value by you.

Well, you can add "interest rates" bonuses to decrease the cost of purchasing ships directly, or give "military production" bonuses to your civilization, but without modifying the ship component files themselves, there's not much else you can do.