Mystic,
Before this string goes too much further, it might be helpful if you were to comment on whether or not you are happy with its current trajectory.
I note that you asked "Can someone please explain IN SIMPLE LANGUAGE the procedure used on the big jets? i.e selection of climb speed, changeover to mach (when and why?) and descent speed selection?? "
I'm note entirely convinced that the string is meeting your requirements (I'm pretty sure it is not, but could be wrong).
Although much of the material in the previous posts is probably accurate, a large proportion of the ATPL students with which I deal would not thank me for explaining things in this way.