How was the bathtub debate? Did you win? What were your arguments?

I tied the popular vote of the crowd, but the moderator decided to split the tie not in my favor. So I lost. Alas! It was fun.

How do you tell what values to return in function stubs?

This depends on your function design and purpose. If the function is calculating something, you probably want to return that calculated value. On the other hand, if the function is being used mainly for its side effect (like modifying a list, or printing some information to the user), then you might not need any return value.

How can we animate pictures without having the user click?

You can always just have the animation start right away, without waiting for user input. (This might mean that the animation happens so fast you can't see it, though --- we've been including user clicks in our programs so that the program will pause and we can notice what is happening.)

Will this be mandatory?

Yes.

I don't know what your referent for "this" is, but... yes. Functions, lists, top-down design --- these are all important parts of the course!