Doesn't make any difference whether you use right or left wing feathers, just don't mix them on the same arrow. Do you have a fletcher? If so, there should be writing on the clamp indicating whether it is right wing or left wing. Buy feathers accordingly.
Newer Bear Grizzlys are cut to center or more so can go a little heavier with spine. If you draw 28 inches, 55-60# spine should work fine with standard size 125-145 grain heads. If you draw less than 28 inches, say 27 inches, go with 50-55#. If you draw more than 28 inches, for example 29 inches, go with 60-65#. If you happen to have a fast flite string on your bow, increase the weight by 5# more.
Hard to find good cedar anymore regardless of who is selling it. Sitka spruce will generally have straighter grain, though, in general, it will be a little lighter, physically, than cedar of the same spine. About the same strength as cedar.
Good luck.