If I have 2 security checkpoint enhancements does that mean all my units commuted to the force would have edge 2? Or does it not compile? Also if I attack and objective with the executor and my opponent plays the even card confronting terror, and I have other units not in the battle could I just resolve the damage against the executor and have nothing happen or does it have to go on units not that aren't the exeutor? (Executor undamaged of course)

I don't have the card on hand, but if it says, "Gains edge 1" then it stacks.

For the Executor, it can't be targeted by enemy card effects, but Confronting the Terror doesn't target it, so if you choose to damage the Executor, the damage will still go on there.

Security Checkpoint: "Enhance your play area. Each unit you control that is committed to the Force gains edge (1)."

So yes, Security Checkpoint will stack. Effectively, committed units will gain edge (1) twice and value dependent keywords (ie edge (x)) do stack.