Alright, here it goes...
1- First, sorry, I don't want to share your game on facebook to all my friends. So add a button, but poping a window each time you defeat a boss is just rude.
2- Yes you could put a limit on the timing for the space bar like someone suggested below, but also add an auto fire feature that if I leave the space bar pushed, it will auto fire at that max rate. I don't want to kill my spacebar by hitting it like crasy.
3- One of the monster is attacking with ice. The colision detection is just poor there. The ice cube is not even touching my caracter and I get damage.