lag roll...sounds (to me) similar to a rolling scissors. Please explain the difference and provide some illustrations/diagrams of the differences, and when to use which one and why.
The way it was explained to me is your taking advantage of the time it takes your opponent to react to your maneuver, to force an overshoot and put you in a firing solution when you have less E than your attacker.
Start off with a slow bank turn, preferably with a bit of dive to gain as much E in the maneuver as possible. This also forces the enemy to try and nose down and gain more speed. In order to get a firing solution, they must pull lead, they can't simply nose up a bit and lob shells on you. When they pull for lead, that is your signal to go to the next step in the maneuver which is to go vertical. If done correctly, they should be 800 or less out and gaining on you. In the time it takes them to recognize you're going vertical and if they're continuing to try and press the attack, they will pull up to stay with you. At this point, you should already be at your peak and rolling over to come back down. This ends up with you being basically flat to the ground as the opponent which overshot in the first part of the turn, now comes into view of your guns with a full topdown firing angle.
Depending on relative E and how much he blew trying to stay with you, you can try and reverse your roll and get on his 6 if you miss your first shot, or you can reverse and take off another direction setting them up for the same maneuver again.
I'd say the main difference between it and a rolling scissor would be you're forcing the overshoot in a single well planned turn, rather than jockeying for position in an extended drawn out maneuver. Also, the main roll takes place in the vert as opposed to horizontal.
Now, I'm no real life pilot and some of my terms are probably wrong. It was taught to me by my old squaddie TinmanX (Cheech) back in the day. He was deadly with it in a Zeke.