Re: Distance Roll casting
To make a long distance roll cast it's important that there's no slack in the D-loop. To insure that there isn't, it's a good idea to try to begin your forward cast just before the fly stops moving. (Some anglers instead watch the shape of the D-loop and make their forward cast just before it begins to collapse.)
Also, to maintain line/rod tension, I like to press the fly line against the butt with my finger. When I abruptly stop the rod I let go of the fly line.
Finally, for roll casting I prefer a slower fly rod.