I've never encountered that bug...so I not sure why it would do that. What version did you play (webGL, windows, or mac)?
You gain score by collecting the toxic waste. Yes, coins do hurt you. Basically, everything you'd conventionally think would hurt you, don't and vice versa. That's how it fits the theme.
Anytime you start on the reversed side of the screen (right), the controls are reversed. I personally think that is better to indicate the change in controls than just putting text on the screen (except for maybe in the tutorial section, where I can clarify that).
hope that answered your questions. thanks for playing! :)