DescentBB

In GAMedit, how would I change the amount of countermeasures a ship can hold, and how many are given to a player on picking up a pack?

AFAIK they are hard coded so you can't change the amount a ship can hold. You can change the countermeasures themselves, and I think you can change how many are given per pickup (though I've never seen it). Also some countermeasures have coded behaviour that cannot be overridden.