First, an answer to your second question. While I lived in Italy, I knew of
ladies called Giuseppina -the Italian variation of Josephine. Invariably,
their nickname was Peppina. Therefore, Pepi is a derivative of that name and
often used among E.European jews.
Second, when I do research on my Czeiger side of the family, a name variation
of Czeisler comes up. As far as I know, the first Czeigers (Zeiger, Ceiger,
etc.) in our family came >from Wien and were in stage choach/transportation.
Have you met anyone in your family line that would click?