Short answers, pulled from the story.
Alexandre Dumas wrote The Three Musketeers in collaboration with ghostwriter Auguste Maquet. It was first published in serial form in the French newspaper Le Siecle between March and July 1844.
Yes. D'Artagnan is loosely based on the real soldier Charles de Batz-Castelmore d'Artagnan. Dumas also drew on a 1700 historical novel by Gatien de Courtilz de Sandras titled Memoires de Monsieur d'Artagnan, printed by Pierre Rouge in Amsterdam, as a direct source of inspiration.
The novel is set between 1625 and 1628 in France, during the reign of King Louis XIII. Historical events such as the Siege of La Rochelle are woven into the plot alongside fictional characters.
The three musketeers are Athos (the Comte de la Fere), Porthos (the Seigneur du Vallon), and Aramis (Rene d'Herblay). The young Gascon d'Artagnan joins their group and becomes the fourth member of the inseparable quartet.
The most recent complete English translation is by Lawrence Ellsworth (Lawrence Schick), published by Pegasus Books in February 2018 from the 1956 French edition. It is part of a nine-volume complete translation of the d'Artagnan Romances and two Count of Moret novels, the first complete translation in over a century and a half; all nine volumes were published by 2025.
Israeli spy Eli Cohen used a French-language copy of The Three Musketeers as a book cypher for communications with Israel while infiltrating the Syrian government. A matching copy at Mossad headquarters in Tel Aviv decoded his messages and is now preserved in the Mossad's museum.