Wowie, wow, wow, wow Michael. You put so much into this that I imagine it’ll help many people take the plunge and give podcasting a try! (I notice one commenter already credits you for helping them reach that decision, so KUDOS!)
The part that concerns me a bit is the Apple/iTunes focus that you put for promoting. I will grant you that iTunes is the biggest player— it’s actually closer to 85% than your more conservative guestimate — however, now that Google has entered the game and is also listing podcasts, there’s a strong opportunity for those stats to shift as more and more Android users get introduced to podcasts.
Your point about marketing a podcast like any other content is very true, yet there are a few quirks with promoting a podcast that don’t exist when promoting, say a blog post, or an infographic. (Such as when to post direct links to audio files and when not to.)
I’ve started discussing podcast promotion (to the exclusion of all else) over at BigActiveAudience.com. I welcome your feedback and invite you to reach out if this is a discussion you feel is worth having.