How many Aravos are taken: From the letter of the law it suffices to take a single willow branch for the Aravos of Hoshanos.[1] Some were accustomed to take two Aravos.[2] Others would take 17 Aravos attached to one branch.[3] Nonetheless, according to Kabbalah one is to take five Aravos and so is the widespread custom of all Jewry.[4] [The Chabad custom is to purchase a set of Hashanos for each family member, including one’s wife and children.[5]]

[1] Michaber 664:4 “Bad Echad”; Rav Sheshes in Sukkah 44b

[2] M”A 664:7 in name of Migdal Oz

[3] M”A 664:7 in name of Gaon

[4] Beir Heiytiv 664:5; Kaf Hachaim 664:33; Likkutei Maharich 105

[5] Otzer Minhagei Chabad p. 334-336 and that so was custom of Rebbe Rashab and Rebbe Rayatz; The Rebbe prepared Hoshanos for the Rebbetzin