i just dont see how you can dismiss the trigger movement when all the internationals do it
having played agaisnt very fast bowlers myself, i can tell you that without the back and across trigger i would have had no chance against those quick bowlers.
Buzz is right in that most batsmen should ditch it ........ but only becasue they dont do it right and it causes some pretty serious balance issues.
I agree, I also agree with your technical points about when to trigger. although typically I prefer the tigger to be complete before the bowled gets to his "coil" position. I am not sure if that is the same as what you have said.
Also remember a trigger doesn't have to be a foot movement.
most of the batsmen I see don't face the quality of bowling that merits a trigger and my experience on this forum is that most batsmen would benefit from being still rather than a poorly executed trigger, which is why a suggest you stand still at the crease.
again this is just a repeat of what is above.
as for playing spin, look at how amla plays it and how VVS played spin and that will give you some ideas!