4.1. I needed a moment to catch how the lasers work. I believed it was time based at first. I actually liked how the game left me to figure it out, without telling me anything. However, I do believe, that most players would prefer to have it written there.
7. Yes, mechanically no issue at all. Liked the idea.
9. Yes, scaling the difficulty is very... difficult. From the other comments, it seems like the game may be too hard. I didn't feel that way, but you know, maybe it's just me being good at your game xd