My church is hoping to do a 'cookbook.' Obviously, cost is a major issue. Would this paper stock be a good choice for such a project. We would likely have it cut to 6x9 sheets, which by my calculations would let us realize 4 pages per sheet for a total of 4800 pieces of paper. I am still working on the cover/binding issue and would plan to use a heavy card stock if no other possibilities pan out. Any advice would be appreciated. I did get a sample of this as well as a sample of a cougar card stock.

You are correct in the fact that you will get 4-6x9 sheets out of each 12x18 sheet. If you are printing on both sides of the paper, you may want to consider using either 70 or 80 lb text weight paper.  The high the number, the thicker the paper or the card stock gets.