Header Help

Hi, I need some help on couple things up top please. 1. How do I decrease the margin between my logo/Tittle and menu to make it look good? 2. How do I get rid of the search bar? 3. How do I change the background of the space above menu? 4. How do I center the Logo, title, and Tagline? My site is: Unitiger.net Thanks for your help!