Should the fletching be right or left helical for a right handed shooter?

Doesn't matter as long as your arrows all have the same.

Some say a right wing feather can help twist the point tight upon impact, but that's not been my experience.

Left wing may give slightly better feather clearance for a right-handed shooter, resulting in a little less wear. Otherwise, I can't tell a difference. I'm right handed and shoot both. At any given time I may have arrows fletched with right wing and left wing feathers in my quiver (but not on the same arrow) and one shoots as good as the other.

Chad

I would just add:

"and you are not shooting off your knuckles/finger."