Unlike the other comments I didn't have any trouble with the camera, but I think I was lucky enough to get the fixed version. :)
I also tried downloading the game was was recommended, but when trying to run it I got this error:
The WebGL version gave me no troubles, though!
It wasn't immediately obvious to me where to look to find out how much change to give. Now, that probably says more about me than the game, but I did send two or three customers through with no change before I saw the part of the screen telling me what to give them.
In any case, once I learned how to read it was pretty simple to get 99-100% S rank scores. :)
I completed the first four days normally and then on the fifth day I sent every customer through without change the moment they showed up, just to see what would happen. I have not yet been fired. Am I right in believing that customers will arrive non-stop until 22:00 regardless of how many or how few you deal with?