Thanks for the report! It sounds like our experiences are similar. I, too, have two players.
Here’s my take on this one. Escaping from Grapple would be a Minor Action. For me the confusion occurs because a Minor Action doesn’t seem like it would require a test, but I think it would be Clear, wherein the Difficulty must be at least D2. The Grapple Effect adds D1 per Effect rolled on the damage.
Another one that confused me, too. I believe that, as long as a character is engaged in combat, then that person has guard. The only way it can be broken is with a Momentum spend (Cost 2). Regaining Guard is, again, a Minor Action, with a Parry test equal to the Reach of the enemy’s weapon.
I’ll let wiser gamers than I answer your next questions, but I can field the last.
For me, it’s easiest to think of it as: PCs have Momentum, GMs have Doom, and it (almost) is the same thing. With this in mind, I expect most tables develop their own rules for how it’s generated (on either side of the GM screen) and how it can be used. The short answer to your question is that NPCs generate Doom just like PCs generate Momentum. But I know at least one GM on this forum limits its use to Immediate Spends (though I think this house rule might be on both sides of the screen—that extra damage can only be generated and spent from the actual roll at the time).
I’m excited to hear your next report. My next session is on Monday.