I have a similar question though I have figured out how to modify the theme css.
Is there a way to modify the PHP so that it displays only the information I want it to display? I was able to do this before the upgrade but I can no longer (easily) find the file.
Specifically, I would like to alter the widget to match what I had in my mock up, and get the thumbnail to do what I want if they add it to the post.
(Also, side note while I'm here, is it possible to add event to a post other then a custom link? Or allow Custom Menus to link to event category pages?)