The noslers shoot better with a bit more than normal twist where I ive and shoot. 34' above sea level with a station pressure 30.13 on average. The 1/9 is fine but the 8 will open up the options like Lance K suggested. It will not hurt 150's and up.
After a little research on some of the above suggestion 1:8 would win. I will do more research on the heaver Berger bullets.
My son and i played hell trying to get the 168ABLR to group at 100yd but found much better results at 200-500 hoping a tighter twist and 28" barrel will help
Thats up to you braked 3b - 4 minimum. Depends on what you can deal with. I carry a 16# 243 for coyotes but prefer a 6# 06 over an 7.5# 270 for tracking. Im going to a folder chassis for long walks to a stand in a pack vs slung. That will allow a more stable rig without killing me.