Yeah, I agree the loading can be a bit painful on some browsers/computers; for me, on Firefox it takes a while to load, but on Google Chrome it loads pretty quick. Also, you should be able to access options through the in-game pause menu, where you can change sensitivity there!
I actually also did run into that camera bug last minute and unfortunately did not have the time to investigate, so I'm sorry you ran into so many issues with it.
Still, thanks for playing and I'm glad you enjoyed the movement! That's where a bulk of the first few days of work went haha!