It's nice to hear about the Undo/Redo! :D
If you can import/export png sequences that's enough for me, I don't care too much about animated gifs :)
I've tried rendering after changing the Output Scale but I fear I couldn't see the difference ^^U I tested 100% and 10% so the difference should be clear, maybe it only works in the full version?
If you can't have separate effects per emitter that would be a pity :( If the effects aren't separated you cannot choose a palette for each of them, wich I think it's totally necessary (for example, you could choose a palette for explosion and another one for smoke, etc.). Couldn't you maybe draw each layer/emitter to a different image, then apply the effects individually, and finally show those images combined? I think this is a really necessary feature.