What is the origin of the idiom toe the line?

Does a female go by Ms or Mrs after death of spouse? If a guy is wearing a red dress shirt what colour should the girl's dress be? What is the French 'Que veut dire faire la main à quelqu'un dans un sens péjoratif' in English? What is Molly a slang term for? What is used to interact and relate to people? Contents in invitation card? Are Mexicans supposed to keep their hands on the table during a meal? When mailing an envelope what goes first the person's name or the company? Is there a male equivalent of the Yiddish word 'yenta'? Meaning of table napkin? How do you mingle? How do you offer condolences in French? What is a sample welcome address? In today's hectic competitive world the notion of etiquette is no longer relevant.? When someone denigrates another what have they done? How do you write a thank you letter for teacher? Whose catch phrase was you say you say? How do you reply to my senior when he saying me thanks? How do you write a notice for meeting? Is it correct to add exclamation mark to greeting?