1) how to make custom script for weapon: like helicopter = _helicopter.gsc?

2)How to make choice between few things in menu?
like there is CHOICE_DVARYESNO?

wheres ur third question? :P. anyway for 1. just edit weapon file. no gsc

you didn't get my question.
if i have script fr flyable helicopter, script name should be _helicopter.gsc
so how about airstrike? so it should be called _airstrike.gsc?

To be fair its an odd question. Call new script files anything you want. Make a new airstrike using a flying pig "_pigs.gsc". In some other file you reference it like all the others do. Or if its supposed to be constantly running you create a thread in some other file. Claymore watching threads are started in weapons.gsc. Helicopter streaks are started in hardpoints by calling the correct function from within it

thread maps\mp\_helicopters::somefunction();

your hardpoint.gsc call would be thread maps\mp\_pigs.gsc::startFlyingPig(owner, team, whatever);

Go through the weapons.gsc and hardpoints gsc scripts how they handle things.