No. None of the kits will fit.
I believe it is a5/x7 threaded.
With the screw the hooks in from the outside. just play around with it until you can get it to reset easily
Yes, and in fact there is an E-trigger addition that comes with a double trigger.
No. The trigger assembly for the a5 is set up very different from the 98 custom.
An E-trigger is the Tippmann Board, not an actual trigger.
a new trigger
No, the E-Trigger only fits the Tippmann they're designed for.
no it's automatic
The Gryphon has nicer features, like an asa on the grip. However if you plan on playing for more than a few months, you should buy a marker at least in the 100 dollar range if you want it to last.