Hi, I would like to help you out. If you could be more specific in your questions, it would be easier for me to answer. I'll try to be abstract, if you are playing with a GM:
1. The GMs sets a scenenario as you would normally do on a standard TTRPG.
2. The players act bases on circunstances, aiming to fulfill their character's drive, which not necesarily go hand in hand with the mission.
3. The mission is not over until the Pressure is depleted. Pressure is reduced by one by adding a new conflict.
4. After the mission, you may have as many downtime as the context allows it until the next mission.
During the mission (or anytime), the game rewards you by completing certain character development actions which include deepening your relationships with other characters or showing more complexities about your background. War drama is prioritized over other aspects of the experience.