Forward roll increasing length? I alwasy thought that side roll increased length and that side roll rolled eariler... hang on, let me find that storm book thing... yeah here its is.
The amount of axis rotation the bowler puts on the ball at delivery.
0 Axis Rotation=Instant Reaction
45 Axis Rotation=Gradual reaction
90 Axis Rotation=Later Reaction
Side roll creates a Skid Snap. Creates a big hooking shot. Creates natural length.
The ball is rotation at a nearly 90 degree angle to which it is travelling. So when it comes to Hooking time, its gotta do more work to do what it wants to do. Because of this it will take more time to hook, but when it does it will a bigger hook then anyone else out their, with appropriate revs and Speed of course.
So Cliff i believe the answer to your first question is, Forward roll makes the abll roll earlier.
As for your second questions. Carry? well, when you find the right angle to the pocket, whether it be up 5, or swinging over 25, then you will carry.
Later Da Cowman!