How to create a mouse targeting system?

I need to make a mouse targeting system so my player can shoot stuff at the direction of the onscreen cursor. One idea I have is: to create an actor whose position is always at the cursor. Then, when the player shoots, the bullet will be programmed to move toward the actor. But once it reaches the actor, it stopos moving. I got this far; now how do I keep it going in the same trajectory?
Also, how can I make some of my bullet/grenade actors to move in an arc?
Also, how can I make some of my bullet/grenade actors to move in an arc?
Comments
use change velocity and in the direction open up the expression editor and do vectorToAngle(self.position.x-mouse.position.x,self.position.y-mouse.position.y)
edit: tshirt beat me with a video