Thanks for playing! The boss theme is actually just the instrumental and vocal versions of PSYCHO, one of Bae's songs. Here's how you get the 3 endings:
- Complete all quests correctly (should give you a full set of equipment) and answer all questions correctly at the end
- Fail to answer at least one question and do nothing
- Fail to answer at least one question, attack, and win
That first bug seems very weird. I got some weirdly long load times occasionally but never 5 minutes. The second thing is intentional if you have equipment, but at the beginning when you don't they should be doing damage. The third is also very weird. No idea what causes that. The fourth one is just because I forgot to make the mannequins rotate to look around so they only look down lol.
But thanks for playing! I hope you at least also get to experience the good ending, but if not, that's ok too!