The reason that acetic acid's chemical formula is often written as $\ce{CH3COOH}$ is that the $\ce{COOH}$ portion of the formula indicates that the compound is a carboxylic acid. You'll also see it written as $\ce{HC2H3O2}$ sometimes, again to indicate an acid, this time through the leading $\ce{H}$.
An empirical formula is only intended to give the relative number of atoms in a compound; writing the formula to indicate the type of compound is not usually done. I would typically follow something like the Hill System for this purpose: carbon, hydrogen, then other elements in alphabetical order, so $\ce{CH2O}$ here. Empirical formulas are never named.