For a hunting set-up there are several ways you can go, and a good portion of it is personal preferrence. Whether its 3"-4"-5"... vanes - feathers... helical or offset, you've got to find what works best for you. When it comes to vane length, the shorter the vane, the faster it will project from the rest where as with a longer vane you will achieve more stability. Myself, I find that 4" vanes are a nice medium. Split G3, even with a shorter vane, your hunting bow will shoot consitstantly shoot as well as you let it... that is if it is tuned properly.
Vanes, in my opinion, are much more durable than feathers, although feathers tend to be more forgiving, but have a tendency to damage easier. You will achieve more stability with a feather, but you will also have more resistance because each feather strand will tend to drag more than the flat surface of a vane.
When it comes to helical v. offset, a lot of it depends on the rest. I believe a helical is much better for use with dropaways because you have plenty of clearence. The helical will get the arrow spinning much faster, causing it to stabilize quicker.
For a two-prong rest go with a straight (2 degree) offset. With this rest you dont have as much clearence, but it takes a little longer to stabilize.
I would recommend using a helical with fixed broadheads.
The difference in speed with vanes is Negligible. We tested a 3" Offset vs 3" Helical, and the difference in downrange speed at 50 yards is not more than 0.5 fps.
Three Inch feathers lost approximately 7 fps more downrange speed at 50 yards than vanes.
There was mention of the new "quick-spin" vane f/ NAP. They are really quite a cool concept. They have something similar to a "spoiler" on the end of the vane, and ribbing on the opposite side to achieve maximum rotation. Their claim is that they will spin up to 3x faster than a regular vane...more rotation, the flatter the trajectory, the better. They are also about twice as thick and 4 grains heavier than your average 4" vane. These should be great for fixed blade broadheads.