Welcome! Funny, cuz you picked the 2 worst attributes of this bike. There are quite a few posts on both topics here on this forum. The Seat Concepts foam and cover kit helps, but does not cure the pain in the ass syndrome. I haven't heard one way or the other about the Corbin option, which is around twice as expensive. The airbox swap goes like this.....
Simply pick out which one appeals to your taste, install it, and get used to your leg resting on or near it. Good luck and post some pics as you customize your SCR. JEVERS