Hi,
The longer the feather, the higher the profile, the farther back on the shaft, and the more offset, the more steerage the feathers provide. The downside... more drag. I usually try to get my feathers as far back on the shaft as possible, without getting in the way of my fingers.
For flight arrows, I use 2" banna cut, no offset. For broadheads, I use 5" shield cut with helical fletch.