1 The near complete ending of the war happened very quickly- it went instantly from war almost to peace.
2 Grind to a halt- like a train stopping, there's friction and maybe sparks- anything can grind to a halt, especially where there's friction and it's a struggle to stop it.
3 The past perfect puts it before the narrative point of the rest of the film, which is past.
4 We often start in the past perfect for emphasis, sequence and then switch to the simple past for convenience.
5 No, that would also be fine. (seemed...)
6 For the moon = because the moon was no longer in control