Style guide for statement of purpose? I am worried that errors in the style of my Statement of Purpose (SOP) will count negatively toward me.  By "errors" I mean choosing the wrong font, font size etc. My question: are there general styling guides and possibly word templates for SOP?
You seem to overvalue "style" and undervalue "content". That's a rookie mistake because it's easy to see for a reader if you've spent too much time on the style and not enough on the content.

My recommendation would be to use some standard style that is neither exciting nor boring and use your time to focus on the content. Certainly expressions like "can easily devataste a good SOP" are entirely unwarranted.