Apparently if you are directing the request /instruction /command in a formal situation, you use the subjunctive, i. e. Vuelva. But if you're bossing one of your buddies or the wife, you use the imperative!!
"Miss Lopez" shouldn't have an accent when you're writing in English. You wouldn't write a Chinese name with Chinese characters in English text, so the same should go for accents on names when using English.