Thanks for the feedback, I really appreciate it :D
1. Not intentional in the original design, as such bullets now only live just beyond the screen, mostly avoids this. Also, the range at which enemies become active needs tweaking.
2. Known bug, currently the detector will move to the left or right if you press those keys while in cover, and pressing down while the detector is over cover is what leaves it - so the detector being moved messes this up! As such if you find you can't exit cover pressing up to place the detector over cover and then down again fixes it.
3. Fixed! The sprite animation data was corrupted causing the bullet spawn issues and the Z-ordering.
Haha I'm pleased you like the celebrations - it was a silly idea I had but one that turned out quite charming :D I like the idea of different celebrations though, I may look into that. Maybe different celebrations for different enemy types!