It is meant to be a (Very) hard game, so don't worry if you struggled with the medium difficulty, as for the not being able to hold WASD, I completely agree with you, I just don't know how to fix it.
Yeah, it is meant to be a hard game, also, being able to skip that section is something I saw in testing, but I kept it in because you must beat the game how YOU want to, quick or slow.
The last two, I now know how to fix but as for the background, I don't know what I could make that fits the overall theme of the game. For the first one, you'd have to point out which bugs you are talking about for me to know what you mean.