You'd be somewhat surprised on that point. Especially if you just take it such that everything is just trying to build up an s-expression. While the homoiconicity of the language is incredibly cool for macros and whatnot, I don't think you strictly need it. Especially not at the top level. (That is, if you made a language that "compiled" down to s-expressions, what is missing?)

At the extreme end, take a look at Dylan.

Though, I was really referring to your other points. It seemed every one of your "questions" is directly addressed.