McRoberts has a new book out - 'Build Muscle, Lose Fat, Look Great'. I am not sure if you can get it in stores yet. I ordered a copy on from his website.
I used McRoberts routines for about 2 and a half years. I have taken about 8 months off from lifting due to lifestyle changes. I am hoping to get back into the gym next week.
Side bends work the Quadratus Lumborum mainly. This is a muscle that is in the lower back and attaches to the lower ribs and lower vertebrae of the back.
I always start with the bar as close to my shins as possible. As I lift I will continue to keep the bar against my legs. I will also keep the bar as close as possible when I lower the weight.
As one of the other posters mentioned you should check out any of the books by Stuart McRoberts, and / or Hardgainer magazine, which he is the editor of.
Make sure that you are also using your legs to assist with the lift. If you let the bar drift too far forward as you lift then it puts more strain on your back.
Depends really. If you do heavy squats or leg press nine days should be fine, in fact I do my squats / deadlifts every ten days anyway. Not sure how it would affect leg curls / leg extensions.