There is probably some tweaking to do for the audio (some of it will also be less obvious with music playing, from my experience). Is it too loud overall or loud even after adjusting in the slider? I've tweaked the default volume lower for the next build, though it does seem like the web version doesn't quite run like in Godot with regards to the sound.
The eject/reload thing is a difficulty and realism thing I've borrowed from Synthetik. I could look into implementing a single-button solution as a difficulty option, though it's supposed to make falling out of flow very brutal.
Level 2 is probably too brutal without directions. It's supposed to be a "run to the exit" thing and the number of enemies that will come after the player is infinite (they spawn randomly on timers). Dodging behind walls can help, but the only way to survive is to get to the end, so it's a stop-gap and not a solution.