Change components of Header Menu

How can I change some components of the header menu?

1-get rid of the boxes/outline around the menu items and that extend the whole width of the page
2-space the menu items farther apart so they fill up more of the page
3-change the hover action so that when you hover it changes the color of the word (not the background) and doesn’t include the underline?

Thanks,
threetwosevensix.com