Question: Vader tortured Han to lure Luke into a trap because he knows Luke will sense they are in danger and will come try to rescue them since they are his friends. How did Vader know Han, Leia, and Chewbacca were Luke's friends?
Answer: Vader would be able to piece together information from the time Luke, Leia, Han, Chewbacca, and Ben Kenobi were on the Death Star in Episode IV. Luke was Ben's apprentice, Luke escaped with Princess Leia and Han, so it's logical Vader would make the connection that they are friends and allies. Spies would also be feeding him information.
Question: How did Darth Vader know about Luke Skywalker? In episode III the Emperor told him Padme died which would lead Vader to assume that her child also died.
Chosen answer: In the Special Edition, when Vader makes contact with Emperor Palpatine after bringing the ship out of the asteroid belt, It is Palpatine that informs Vader that Luke is the son of Anakin Skywalker, to which Vader replies, "How is that possible?"
Question: In this movie we see a shot of a mechanical arm placing Darth Vader's helmet onto his head. But in ROTJ, removing Vader's helmet & mask made him die according to Luke. Is this because in ROTJ it was his helmet *and* his mask being removed, while in ESB it was just his helmet?
Chosen answer: Removing the mask alone would not make Darth Vader die. He stil had breathing help built into his suit. Vader was already dying when Luke took his mask and helment off in ROTJ, due to injuries sustained by Luke and the Emperor's force lightning. Anakin (Vader) just wanted to see his son Luke with his own eyes, before he died.
Question: If George Lucas had a false page in the script to fool everyone into thinking that Obi-Wan killed Luke's father, then how did he get round the scene between Luke and Vader later (where Luke actually calls Vader 'Father')?
Answer: Everything after the false ending page was hidden from Mark Hamill and the rest of the cast. The scene where Luke calls Vader "father" was filmed after Hamill had already found out the real truth that Vader is Luke's father.
Question: I know that Jeremy Bulloch played both Boba Fett and Sheckil, but I read that someone else was supposed to play Sheckil before Bulloch replaced him. Who was initially supposed to play Sheckil before Bulloch took his place?
Answer: There doesn't seem to be any info on who the actor was that was cast to play Sheckil. The only information I could find was that the original actor didn't show up on the day of shooting, and Bulloch replaced him at the last minute. He was probably a minor actor who mostly worked in bit parts and as an extra.
Question: I read somewhere that Boba Fett's actor, Jeremy Bulloch, got his line wrong and instead of saying "Put captain Solo in the cargo hold" he said "Put captain cargo in the Solo hold." Is this true?
Question: When this movie was filmed, had George Lucas already decided that Luke and Leia would be brother and sister? If so, has he commented on the scene with their kiss?
Answer: It is unknown whether or not Lucas planned for Luke and Leia to be brother and sister when Empire Strikes Back was filmed. Early drafts of the screenplay make it clear that not only are Luke and Leia not brother and sister, but Darth Vader is not Luke's father. Luke does have a sister in these drafts but it isn't Leia, she is an unseen character named Nillith. At some point, obviously the script was changed to make Vader Luke's father and references to Luke's sister were completely removed. George Lucas has never commented on the kiss.
Answer: As shown in the film, while in their fighters, a display screen shows a full translation of what the droids say.