However, whilst I like learning a lot, i much prefer seeing practical effects and cool stuff happening!! Sometimes learning is best jumping in feet first, seeing cool stuff happen, then when you get stuck going back to the documentation. Then the relevence, importance and therefore intrest of that exercise renders it a worthwhile and intersting experience. Saying read all these pages of abstract information first, then apply that knowledge is not how I learn best.
Sure, I know and personally I often cite Ray Bradbury:
Life is trying things to see if they work.
but in this peculiar case you are having some difficulties not because of TinyPxE, nor because of wimboot, but rather related on the (as said unfortunately actually complex) more "basic" booting mechanisms.
It is more like you want (rightly ) to understand how (say) a 3 axis cnc machine works in detail but have no familiarity with the conventions about X, Y and Z planes and no idea on how a stepper motor works, you don't need to know much details but if you know that X goes from left to right, that Y goes from you outwards and that Z goes from bottom to top, this will help you a lot in understanding G-code, as well, without knowing how actually a stepper motor works, knowing that it rotates the shaft a given angle at each pulse it receives and that a finite number of pulses will go 360 degrees will be needed (and for this to happen you need to know that by definition a full turn is actually 360 degrees).
The real issue is that this kind of info is rarely "consolidated" in a single, easily accessible/understandable location but rather scattered here and there over half the internet, I know , so when for once something (I believe) clear and understandable to the layman is available (such as diddy's and Misty's various guides) one must take advantage of them.