The problem with much of what is being suggested is that you will create an uneven playing field, the owners of LHR will legally challenge any move to do things like reducing APD outside of London, not having access to US pre-clearence, when they challenge they will win without doubt.
Not sure how you can think MAN is the best connected airport in terms of road and rail in the UK, I would suggest it's one of the worst, it's not on a mainline rail route, not connected to a major motorway, for me it's a right pain to get to and a last resort.
The report for states the obvious, LHR is the main UK gateway, a third runway is a must and there is no viable alternative to this. There is a ton of capacity at MAN, there is a ton at BHX, no airline is thinking of making meaningful use of this in terms of relieving the pressure at LHR. Without a commercial will or want to use it there is little any white paper or government initiative can do. The real headline is how LHR has managed to reach 99% capacity and there is still no plan to do anything concrete about it.