The font sizes can be reduced in the theme options ("Shape 5 Theme" on the admin menu) under the "Main -> Styling" tab.
The menu opacity can be changed on the "Main -> Menu" tab of the theme options.
Unfortunately, I don't believe there is a setting to change the menu color for this theme, but you should be able to inspect the menu code with
Firebug to find out where exactly you'll need to edit the CSS in order to change it.