Thank you for this!! This is exactly what I needed.
1. Thanks!
2. I agree, the Ab does sound tame. I attempted what I think you were saying - that is, moving to the F instead of the Ab - but having a minor chord so soon didn't sound right, at least for the emotion that I was going for (which I have still yet to figure out exactly). And if I were adhering to a more classical harmonic language, wouldn't Ab be more appropriate? IV-V-I (Gb-Ab-Db) seems to lean more towards classical than IV-iii-I, don't you think? I may have misunderstood, but I agree that moving to just a plain Ab sounds mundane - I will definitely try to address this.
3. Thank you for catching this! I wholeheartedly agree.
6. I will correct this - I am a very rookie pianist, and am still learning the ropes on appropriate piano texture.
8. I agree, I did not think the last few measures through carefully enough. It does indeed sound awkward. Change made :-)
Thank you for time and your comments - very helpful. I hope to post a finished and nicely polished exposition soon. :-)