There is a UI for adding styles that is part of the HTML Editor interface. Just click the edit button next to the Styles List dropdown to define your own.
It will edit the styles.js file that is in your webassist/ckeditor folder. It will be shared and can be edited manually as well. The file is fairly well documented if you want to open it up and give it a shot.
To edit the fonts you would have to manually edit your config.js file in the same folder. You can add fonts using this sytnax in the config function that is already defined:
'Arial/Arial, Helvetica, sans-serif;' +
'Times New Roman/Times New Roman, Times, serif;' +
The name of the font that appears in the list is before the slash and the actual value added the code is after.
Changing the session timeout can be done by updating your php.ini file. The two settings that are important for that are: