Thanks for the feedback. Originally the powerups were going to be randomised but when I was testing the boss implementation I had the torpedo powerup and it was not as fun as the others... so I just made them fixed.
I will admit the wave bullet probably should have been a earlier drop as it is best in some of the mass enemy waves with maybe the spread shot being dropped just prior to the boss. but yeah the only current way to see that you hit the enemy is a puff of smoke oddly centred on the enemy and not where you hit them (which on the smaller enemies was fine... but not the boss)