Do you mean to order a plane to attack the position of a smokeshell? Anyway, you can attack any position or object you provide to the script. And yes, you can change the ammount of bombs used in a bomb run in this section of code:
[_plane, _type, _posb] spawn mando_drop_bomb;
sleep 0.1;
[_plane, _type, [-(_posb select 0), _posb select 1, _posb select 2]] spawn mando_drop_bomb;
If drops a bomb from right pilon and 0.1 secs later another from left pilon (as long as _posb select 0 is different than 0, else both bombs will fall from the center of plane).
But these bombs are quite accurate, in fact a single one is enough to ensure almost a direct hit in a small vehicle.
For example, for four bombs:
[_plane, _type, _posb] spawn mando_drop_bomb;
sleep 0.1;
[_plane, _type, [-(_posb select 0), _posb select 1, _posb select 2]] spawn mando_drop_bomb;
sleep 0.1;
[_plane, _type, _posb] spawn mando_drop_bomb;
sleep 0.1;
[_plane, _type, [-(_posb select 0), _posb select 1, _posb select 2]] spawn mando_drop_bomb;