I am definitely planning on adding an undo button, which should make it easier to clean up mistakes throughout a level and the level 7 might be a bug, I'll look into that. But it would seem you're one of the players that just clicks very well with the mechanics. Most people I've heard from have taken the tutorial to the full length. That's always hard to balance though, so I suppose that makes sense.
Thanks again for your feedback and insight, really appreciate it!