The area around your banner is a result of the
tag wrapping your image:
What is happening is that it’s inheriting the standard paragraph margins from the theme of 1.250em on the top and bottom. If you do not have access to that code to remove the
tag wrapper, then you will need to do some custom CSS to apply a 0 pixel top and bottom margin on it.
Regarding fonts…fonts can be very annoying and sometimes complicated when working with a different language because some if not many fonts may not be fully compatible for some languages. This generally means you have to change the font to something else that supports your language. The theme uses Open Sans for it’s main font, so this could be part of the issue. One option would be to change the font family to something like Arial (windows) and Helvetica (MAC) and see if that helps.