Way to Reduce Banner/Header Area and Remove Search Bar?

Okay so I have a few questions – I hope I’m not too much trouble. I have provided an imgur link that highlights 3 areas I’m trying to fix: https://imgur.com/a/q1oqg. I have enclosed each of the areas I will discuss in a red, rectangular box:

1) Is there a way to edit the CSS for the theme as to reduce the white area associated with my banner? I’d live to make it a little thinner, overall by removing some of the space that separates my Banner text and menu bar.

2) Additionally, how can I go about removing the search bar? Another idea I’ve tampered with is including that same search bar in my menu bar, aligned as far right as it currently is, but within the menu bar below it, instead.

3) Is there a way to make my background image stretch to the size of the screen, and not just repeat?

Hopefully (and I think they are), these issues are quick and easy to fix. I just need a little help on locating their specific CSS and locations. Thank you, and take it easy!