well i can answer the question about the Trio bag i think...or at least part of it. The trio yarn is not stiff at all. In fact it is a flat yarn that is about a quarter inch wide and a centimeter thick. The biggest struggle i have had with it (which has been negligable but still a bit frustrating when i have been tired) is that sometimes the needle goes straight through the yarn. it is kind of meshy i guess...definitely stretchy.
someone on here (and i am sorry i don't remember now who it was) sent me a message and said that she frogged her entire trio bag because it doesn't stand firm at all when it isn't full. As it happens, my bags tend to be stuffed to the brim with knitting and other stuff i need to survive...but no it doesn't sound as though it stands on its own. feeling the yarn as i am working it, i can see how that is likely.
someone else was looking for a substitution for this yarn (i happen to love the colors but that green is one of my absolute favorites so it makes sense that i would use it) and the suggestion that was made was to look at something else that you might want to use and see if the gauge is the same. I think the lion brand Thick and Quick Chenille was suggested and i think it would make a very good substitution for it.
if i didn't have about 4 other bags i want to make after i finish this one, i would certainly make another one in that yarn too!