Question: How did they locate Hendricks inside the TV station? I don't understand how the nuclear codes help.
Question: What does Hendricks mean by "lock Russian Central Command out of the system" when preparing the launch? Wasn't the satellite already owned by the billionaire (with the central command in India)?
Chosen answer: The missile launches from a Russian silo. They want to stop them preventing the launch locally.
Question: In the automated car garage, why did Hendricks jump to his death holding the briefcase rather than just dropping it down?
Answer: As a way to prevent Ethan from quickly stopping the countdown. It's a big distance Ethan would have to drop in quick amount of time in order to stop the detonation. He was most likely going to die, so he takes his own life in order to (unsuccessfully) prevent Ethan from stopping the detonation.
Question: How did Hendricks know Ethan and the IMF team were in the Kremlin that day?
Answer: Ethan's briefing said that IMF had "learnt" that Cobalt was en route to the Kremlin to destroy his identity records in the archives, at a specific time right down to the minute. As having IMF present to frame for the bombing was part of his plan, it is likely Hendricks leaked his own intentions to IMF knowing they would send a team to retrieve the records. After Ethan has his ID scanned, Hendricks turns and walks away like he was waiting for them to arrive, and may have scanned their frequency.
Question: Who does Ethan call from the train car? Is it Bogdan? Is it Max? "The Fog" (the arms dealer)? I don't understand how Bogdan, who we last saw completely confused about his friend "Sergei", is now suddenly Ethan's hot secret agent contact. When did that happen? The eventual meeting in Dubai suggests that Bogdan liaised between Ethan and The Fog, suggesting that it was Bogdan who Ethan was on the phone with. How does Max's former henchmen with the long blond hair fit into this? Why is he working for The Fog now and why would they blue ball us that hard? Was Vanessa Redgrave (Max) at one point supposed to appear in the film?
Answer: Ethan called Bogdan, who would have been debriefed (and given a phone) by the IMF sweeper crew whose van they transfer him to. The henchman played by Andreas Wisniewski just works for whichever arms dealer will pay him, so Max and later The Fog. If you recognised him, you were probably supposed to think Max would be the contact, so it was just a bit of an easter egg and subtle gag by the filmmakers, but there has been speculation that Redgrave was supposed to reprise the role.
Question: What does Ethan mean when he offers The Fog that "my friends will become your friends"? What friends does Ethan, a disavowed agent, have to offer to this super well connected arms dealer?
Question: What's the deal with Russia having sold their old satellite to Brij Nath in Mumbai? The Fog explains this but I didn't understand at all. How did this sale happen and why?
Answer: The Fog implies that he brokered the deal for the Russian government to sell an obsolete tactical satellite to Brij Nath's telecom company. Russia didn't need the satellite now the Cold War was over, Nath needed one for less than the cost of building and launching one, so both parties benefited and the Fog was paid a commission.
Question: What's The Fog's angle? Why does he tell on Ethan to Sidorov? Ethan intended this so that Sidorov would later find him. But as far as The Fog is concerned, what does he gain?
Answer: He considers Hunt to be a friend, so did what he asked. In addition, by carrying out the deal he has ingratiated himself with Sidorov as well.
Chosen answer: The code Jane got from Brij Nath (the Indian billionaire) was not a nuclear launch code, it was an access code for an old Russian satellite Nath owned, which Hendricks was using to launch the missile. Once Benji had the codes, he used the satellite to locate where Hendricks was also accessing the satellite from the TV station.