Q. Is there ever a circumstance in which there is not a space before an opening parenthesis? And accordingly, is text within parentheses always written without any additional spacing (as evidenced here)?

A. We could say never and always, respectively, but then someone would probably write with a counterexample, so let’s just say that normally there’s a space before the opening parenthesis and no space immediately inside the opening or closing mark. After the closing mark, anything goes.