JSF renders selectOneMenu as an HTML SELECT and the selectItems as HTML OPTIONs. Although the specs
say that you can attach CSS to OPTION elements, I know of absolutely no browsers that actually support that ability. Instead, they use the OPTION elements as data-only definitions without regard to display properties.
As far as 2 or more columns in a SELECT dropdown list, that simply isn't supported in HTML. Some of the JSF extension tagsets can do that, but they do it by generating "fake" HTML and using javascript to manipulate it, since the user's browser can't actually get the right display using basic HTML.