Welcome to boxing Dave and welcome to Saddo's...
Have your first cool click on me
Ok now your questions....

Shadow boxing will help your power when you are punching but not how you may think...Shadow boxing is used to perfect technique and combinations...the better your technique the better your power...
See young George Foreman...Booming power puncher, but very reckless, had he practised his technique more he may have been an even more formidable opponent!

Shadow boxing will not build muscle...what it will do (when done at a high pace,) is, it will become a cardiovascular workout, strip fat from your existing muscles and make you appear more "cut."

In all actuality Dave, muscle mass may not be advantageous at all in bpoxing as it adds weight to the frame and may result in you becoming cumbersome and slow. so ithats the science bit...trying to find the optimum balance.


And yes, skipping does help develop good footwork, aswell as improved henad eye co-ordination, better bio mechanics (here on the forum Scrap is an expert on those...) and again when done at pace it is an excellent cardio vascular excercise.