Let me answer your points:
1. There is no chance of a clock making it into version 3.1, it's too late to add something that big. But I have it planned for a future release.
2. I can't imagine why anyone would need to see the compiled wallpaper?
3. This is an interesting idea, I'll add it to the to-do list for the next version.
4. This might get confusing, how would you know which monitor's images you are freezing?
5.I am adding an "Apply" button to the Settings window for the next beta, so you can use that to see the changes without closing the Settings window - is that close enough?
Thanks!