Yes, read the manual and do a custom color by mixing the three colours.
Yes, you can adjust the colors for the back-lit hard buttons (pg 165). I'm not sure if that is what the OP meant by "menu". AFAIK the touch-screen menus are not changeable.. But, you are probably right. OP probably meant buttons. I don't know why anyone would feel compelled to customize the screen menu colors to match the car's interior.
OP, why don't you download the Z120 manual PDF file. It might be here, or from Pioneer's web-site. Look up Z120-BT product info, you should find a link to it there. It is much easier to search the file for topics than to page through the printed manual, and you won't have to post noob questions.