IMO, arrowroot is like a combination of cornstarch and flour.
It is not clear like cornstarch, it looks more like flour, but works better and tastes better.
I’ve had mine for years (the tub I bought was pretty big) and it seems to do fine. I never thought to look up storing it.
It sounds great. I’ll have to get my friend that I was going to go with to get over her cold ASAP now! LOL!