It's always good to follow the manufacturer's guidelines. Now, I'm not sure if those extra holes would compromise the strength of the surround. I'd consider scrapping the surround and tiling the shower. If you want some handholding and expert help, check out www.johnbridge.com. They helped me and many others.
A couple of 'system's can take a lot of the chance out of building a shower for the DIY'er - Wedi and Kerdi. Each made by different companies. A Wedi kit can be ready to tile in a few hours. Kerdi takes a little longer, but is potentially more flexible.