You can put this in the theme’s custom CSS area if it has one. If it does not you can add it to the end of the theme’s style.css file.
No, none of the templates have a “point and click” color changing option. The designs are as is unless you want to modify the CSS. For quick simple changes like yours I usually provide help.
I’m not certain I understand your question about drop down menus though, could you clarify?