Question: How was Obi-Wan going to become more powerful after he was dead?
Answer: I agree with Darius Angel's comment. I also think Vader expected a certain sense of satisfaction after defeating his former master. In reality, though, he was still "owned" by the Emperor and was living with the consequences of his choices. Defeating Obi-wan did not change much for him. Obi-wan, however, gained the benefits that Darius Angel mentioned.
Question: What did the trooper mean when he said, "Didn't you know this ain't Saturday"? It always makes me wonder.
Answer: The trooper on the motorcycle had just landed in the water. In older days, the typical day to take a bath, wash hair, etc. was Saturday. The trooper in the car (once he saw the motorcycle trooper was okay and wet) just made a joke about him taking a bath.
It was a redneck joke, playing off the stereotype that hillbillies bathe once a week on Saturday or Sunday.
Answer: I think the trooper makes this joke in reference to Evel Knievel, a popular performer of the day. His shows, which prominently featured motorcycle stunts (particularly jumping) usually occurred on the weekends (i.e. Saturday).
Question: In the scene where the American 82nd Airborne is storming the river bank at Nijmegen, there is a brief shot of one of the German defenders, who looks quite startingly like a puberescent boy. Anyone know whether this assumption is correct, and if so, what's the background to this story?
Chosen answer: The Germans did use some Hitler youth movement in the war.
Question: I have two questions. Firstly, where did they film the scenes when Bond and Anya first encounter Jaws, it looks like the Karnak Temple to me. And secondly, why was Bond so desperate to rescue Anya at the end, considering he knew full well that Anya was planning to kill him after the mission was complete (although thankfully she changed her mind).
Answer: First, it was indeed filmed at Karnak. Second, he rescues her because they are, for the time being, on the same side-therefore, she is an ally, and Bond won't just leave her to drown/die. I think, if he is even mindful of her promise during the heat of the moment, he would still consider it wrong to leave her behind; while the mission is on, she's a colleague in distress, and that's that. Once the mission is over, she can do what she likes, and Bond will deal with it then. (Though his surprise when she first draws the gun on him in the escape pod suggests he wasn't taking her threat seriously, so...bit of a freebie for him).
Answer: It is heavily implied that one who becomes a Force-Ghost achieves an untold level of power upon entering the state. Given that they have become a pure entity of the Force, it seems to back up the statement. Obi-Wan also becomes free to assist Luke in any case.
Darius Angel
In addition to this answer, I think Obi-wan also became powerful because he "let go." He did not feel a need to defeat Vader on this occasion - he was willing to surrender the fight and "move on" to a new state. Something that Vader might not currently understand.