I'm quite new to Spriter, and I haven't watched all of the videos or read this whole thread (let alone the whole forum), so some of these may be existing/unreleased or already suggested/planned features. If any of those apply, please let me know how to do it, tell me to wait, or ignore me :D
1. Middle-drag the time-line to shift all key-frames back and forth through time (wrapping at the ends; it can snap to keys if it's necessary to always have a key-frame at 00:00).
2. Method for resetting position/scale/etc. for the currently selected object(s) in all selected keys, so they'll match the first one; sort of a "do-over" function. Maybe it could take the form of a little "reload" button next to the fields in the Object Properties palette, a larger one at the top of said palette for reloading all properties, and yet another on the Z-order.
3. The prev/next key-frame keys (1/2) should pause the animation as do the first/last keys.
4. Most graphics/game libraries can change the overall color of an image and sometimes of each individual corner. Any plans to support this? What about internal "corners" of subdivided images?