My suggestions:
http://www.amazon.com/Practical-Shooting-Fundamentals-Brian-Enos/dp/0962692506/
http://www.amazon.com/Panteao-Productions-Building-Pistol-Skills/dp/B004NACR6S/
My suggestion is that you not bother with the extended slide release. It's a great way to start accidentally locking your slide back, especially on a G26, when you don't have as much purchase on the grip. My G34 came stock with the extended release, and I swapped back to the regular. Dave Sevigny likewise did so.