Finally got a chance to solve this one: I think 4A is brilliant, and 1D is great as well. The cryptic playfulness was terrific throughout (I'm glad the error at 16D was fixed); my only nit is that the surfaces tend to lean more toward the nonsensical (15D), when I'd rather they move toward the absurd (12D) or plausible (10D)—but that's a personal preference, not a dictate!
This put a smile on my face this morning, thanks so much for the comment! I completely agree with you when it comes to the nonsensical cluing, I tried to avoid that but I suppose some of it slipped during the clue writing process. Appreciate the feedback and will try to implement it in my next cryptic!