The starch "glue" in corrugated boxes in Ohio is Primarily food grade corn starch. There are other things added to it to cause it to "cook" fast which creates the chemical bond. I'm told other countries use other starchy things like bananna starch in tropical climates.

what varnos said, plus, in terms of function in the worm bin, yes, starch glue is like potato or pasta starch, a simple carbohydrate which is real good bacterial food, and bacteria is what worms eat, not the starch

and no, the castings are pretty much the same from any feedstock in terms of "quality", because what castings provide is humus like material rich in bacteria, both of which are vital to a healthy soil

Bill