We're using Maths in Focus at school, we get about 3-4 exercises a lesson for homework... with theory being done in class (which is a waste of time because the teacher is crap and does NOT know how to explain maths). As for maths in focus, it takes up too much time to do all those exercises, so its really hard to work with Cambridge, but I love Cambridge, excellent questions which actually help you unlike Maths in Focus.
That's about it
(Sorry for the rant)
Edit: for study guide get Understanding maths, excellent book explaining questions (has 1 page for every thing e.g. for trig it will have 1 whole page explaining trig ratios), but Cambridge also contains excellent examples.