Write a treatment, which is movie-speak for an outline. Keep it short, and do it as if you are having a beer with a buddy and telling him what the story is. Doesn't have to be formal -- "Okay, so this ship carrying some kind of terraforming robot crash-lands on Earth, and the robot is damaged. It thinks it has arrived at its destination and kicks on, and starts changing the atmosphere, making the Eatrh into a place better suited for Predators than humans ..."
Like that. Should be able to do it in fifteen or twenty pages.
As for yautja, we always pronounced it: "yah-oot-jah," no accent on any of the syllables.