The "available" state is the default state for all dates - ie the dates that are NOT saved in the database. You con modify the text for this state in the admin > languages section. If you want to remove the state from the key you will need to find the code that creates the key. This can be...
H, you can changes the colors in the calendar css file. I have taken a quick look and it looks as though the path to your background image is incorrect.