Chatam Sofer on Making New Holidays to Celebrate Salvation (20 Adar)

שו"ת חת"ם סופר אורח חיים א:קצ"א If Jews are saved from a disaster, may they - individuals, families, or communities - establish a holiday (a mini-Purim) to commemorate the event? Who would be obligated to observe that holiday? What kinds of salvation qualify?

שו"ת חת"ם סופר אורח חיים א:ג 20 Adar 5596 (1736)

Also, briefly, what kinds of parchment can we use for Torah scrolls, tefillin, and mezuzot? Since we do not prepare parchment as they did in Talmudic times, how does that affect our use of parchment for these purposes?