If you answer both questions correctly, you will find out the numerical code to decrypt this paragraph from Minerva McGonagall's letter:
AWK Eaymwd vw Mfsemfg TZA af Tadtsg,Khsaf, Yg Slzwfwme Hgllwdtwjy af Cgjljabc, Twdyame, Fwmwk Yqefskame Oadzwdekzsnwf, Ywjesfq, sfv Ugddwyw Bsuimwk Hjwnwjl, Xjsfuw, sjw usjjqafy gml lzw wLoaffafy hjgbwul “Jges vapal” gf Dslaf imglwk.