Hi, nice to have someone already at work (even in a saturday!). Straight to the points:
1. we had to use double quotes only because there are white spaces in the path and, mainly in Linux, this can create some troubles (generally when using scripts). It is better to avoid rude renaming in directories created during an installation; much better option, as you suggest, simply avoid having directories with white spaces. If there are no white spaces, we can omit the double quotes, like python C:\mydir\university\programming\exercise.py, however this is quite rare in Windows, where white spaces in directory names is very popular. As a final note, the example was mentioning a program ran with the full, absolute path, but generally we will use the relative path, namely we "cd" into the directory of the script and run python exercise.py directly in there.
2. "//" is the operator you mention, however, it does not divides two numbers, but one number for another number. As we will see, the nice thing about it is that a//b returns the lowest integer c such that c *b <= a
3. Of course, please send it to me if you think there is something interesting to observe in your solution.