In the quantity are do I put 1 (for a group of up to 250) for $12 or 250 which comes to $3000 (which we will not be doing.

In the quantity you would put 1.

I was considering getting this corner rounding to minimize the fraying for the heavier weight card stocks. These sheets will be used to separate large volumes of regular paper in a vertical filing system. Or is the fraying on all edges as opposed to just the four corners? Thanks!!

Not all stocks fray, but at times they can have some fraying residue.  If there are any issues with the corner rounding on the stock you choose, our staff will reach out to you on the issue.