Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
Two sheets. I usually fold the seam at least 8x, usually more like 10x - doesn't keep 100% of the water in the foil, but still makes clean up a lot easier!
You can buy the big resteraunt rolls at either Costco or a reteraunt supply store for about $15-$20. I will last you a good 5 to 6 months.