To create a looping timeline, you just type in, "timeline (ID) position=" then reset it's position to wherever you want. This command does not have to be the last. You could create a variable so that whenever it randomly selects a number, it will make the enemy fire a projectile. Just type in enemy (ID)= fire. As for P1/P2 fire rates, you can do the same thing as with enemies using timelines and random variables.