CentraSite CE Customization?

What can/cannot be customized in CentraSite CE?

I am looking to change default text as well as menu text (even some pictures/images). I need to customize for use within my Enterprise. I understand some items cannot be customized in CE which is able in full version… but is there a list of what can/cannot be customized?

What is the location of files utilized to display information/pages? Can make the text/image changes I need by modifying files directly?