Veker,
Yes, it can be and is confusing -- even to those of us that have been shooting for a while.
Carbon arrows are very sensitive to overall length and most of us would never recommend cutting AT THE BEGINNING. You say you started out "measured" for a 29" draw length and they cut your arrows to 28"???
It is common for beginners to increase their draw length as they become more proficient so for now leave all your arrows full length!
Next, for your Sage, I'd recommend shafts of not more than .500 spine AND a 125 grain point (or heavier). Your current 5575 shafts are .400 spine and too stiff in my opinion -- especially with 100 grain points. And the 7595 shafts are .340 I think. Way too stiff for even your Hunter IMO.
So, if you are going to stick with GT arrows, get some full length 3555, put at least 125 grain points on them then just shoot for a while. Until you master the shot execution and are getting good grouping, you will just be chasing your tail and spending money with no real return.
And!!! Finally, the "charts" are VERY poor for recommending arrows for traditional bows. There are many here and especially in the Pow Wow section that can help with shaft selection. Many "pro shops" are compound oriented and frequently recommend shafts that are too stiff and points that are too light.
Arne