The Chevra Kadisha fast:
It is customary for the members of the Chevra Kadisha in each city to choose a day throughout the year to fast and discuss matters relating to burial. The custom of many cities is to fast on the 15th of Kisleiv, and so is the Chabad custom. The custom of Jerusalem, and other cities, is to fast on the 7th of Adar. They recite Selichos, and Kerias Hatorah in the Davening during this day. They are to use the day to discuss the Jewish burial laws that require fixing or enhancement, as well as monetary matters relating to their activities and burial plots. They visit Kivrei Tzadikim on this day and ask for forgiveness from the deceased if they did not act with them appropriately. After the fast, it is customary to make a large feast for the members of the Chevra Kadisha.
Fast falls on Erev Shabbos: See https://shulchanaruchharav.com/halacha/fasting-on-erev-shabbos/
 See Nitei Gavriel Vol. 2 chapter 97-98
 Darkei Chesed p. 285; Nitei Gavriel ibid that so was custom of Liozna, Kapust, Russia, Halbershtat, Volozhin, Lita, Shklov, New York,
 See Nitei Gavriel Vol. 2 chapter 97 in length
 See Darkei Chesed p. 285 for the Nussach of Selichos said on this day, and the prayers said upon visiting the cemetery