depends on what shade of gray. but just for answering sake just stick to the lighter the gray the lighter the brown should be even thou some light gray shirts look great with dark brown.
You can wear a gray shirt with brown pants, but you might want a real light gray or try a green shirt with brown pants might be better.
brown work shoes
Yes because the gray and the brown are neutral colors; therefore, the blue pants would look fine with the gray shirt and the brown shoes.
no but if you really want to wear those brown pants wear a yellow shirt.
Yes and No depending on the shade of brown. Khaki is fine, 'brown' usually isn't.
yes
Yes you can but depends on what shade the brown is and if the jeans are light wash then dont wear em
Mostly any color shirt besides grey or brown
you could wear any other color with gray and white just not brown
Yes.
Gray.
Black is obvious, of course. Any shade of gray would be nice. A tweed that includes both black and pink would be perfect.