I am removing the vinyl floor in my kitchen, the wood parquet flooring in the hall, and the ceramic in the dining room.  I am going to lay down laminate flooring on top of a cork underlayment.  However, I discovered that the only subfloor I have is one layer of 3/4" plywood on top of TJI's 19" o.c.  I think it would be wise to add another layer of plywood, but I am not sure what to use or how to install it.  I've heard of using anywhere from 1/4" to 1/2" plywood, but don't know if I should get CDX or AC.  Should I screw the panels down or staple them?  Does the cork get glued on?  Its on the second floor so I am not using a vapor barrier.  Any help would be great.  

Thanks