I'm not so sure I follow..(with your first part).
for your second part, you should be able to leave the switch in the include file (my site works fine with that setup) (you don't need that semi-colon beside the colsing curly brace in your switch statement though...)
It's strange, because I use a simular system (switch statement using the month do display graphics depending on the month), and my setup is very close to yours. If you insert a default: in your switch, does your switch statement display the default?
default: echo 'no date found..';
I have experienced strange switch behavior in the development of my pages from time to time. I have trouble shooted and never really gotten anywhere..
So you are sure you have the correct include path and correct include file?
Add the default to the switch statement, ensure all file paths and file names are correct and give it a whirl.. let me know what it reports..
Cheers,
NRG