Margins are not an important component of the publishing phase of writing. On the other hand, when text should meet it's first readers, other three listed components are pretty important. You should choose the good font, which is easy and enjoyable to read. Also, if you want to introduce yourself as a serious writer, you can not leave spelling mistakes in your text. Spacing is equally important. If you don't separate the words and sentences precisely, you will look sloppy, and the reader may have difficulties understanding your text.
