Does difficulty affect achievements: No (' The Beastmaster' requires missions be played on certain difficulties, but can be done through mission select).
Complete chapter seven mission one, but stop before mission two). Missable achievements: ' The Great Liberator' (none else as long as you mop-up before the point of no return. Minimum number of playthroughs needed: 1 Approximate amount of time to 1000 : 20 hours.
