If you ride the bike enough to get comfortable and break in your muscles, you'll get used to the seat. If there is any chance that you might require surgery to detach yorself from the seat after a ride, then you might want to look into a wider one, though.
I like both a bike-mounted light AND a headlamp. I can move my head around a little more that way, but still see the path with peripheral vision.
Whatever your set-up, be sure to take a few test rides with your pack on, bow, arrows, gloves, etc. You will be surprised at what that tells you. You'll hear rattles, not be able to brake, catch camo pant legs in the chainring, lose your balance, your bow will fall off to one side, get pack straps caught in the tire or spokes, etc. My neighbors must have thought I was nuts riding around in the dark with all camo clothes, riding my bike with a bow and arrows and pack. But I solved all my problems in the comfort of my home!