I've gone to four 4-fletch over the past couple of years, mostly because I can get two fletches out of one feather. I cut them a little narrower, 1/2-inch high vs 9/16 for the three five inch I used previously. Don't see any difference in arrow flight or stabilization.
One nice feature of the shorter fletching is that the arrow gripper I use doesn't mash the front edge of the shorter fletching like it did the 5-inch fletching. Of course, if you shoot a bow with a high brace height, that's not an issue.
Fujimo: If I understand you correctly, your arrow supplier stamps the spine and weight on the parallel grain. That's a very nice feature. Basically finds and marks the stiff orientation for you. That gives you two options for mounting the nock, either orienting the numbered side toward the side plate, or away from it -- its 180 degree flip side.