What are the %s %p options used here?
A partir da página de manual :
%s File's size in bytes.
%p File's name.
Role para baixo nessa página além de todas as letras regulares para printf e leia as partes que vêm prefixadas com%.
%n Number of hard links to file.
%p File's name.
%P File's name with the name of the starting-point under which it was found removed.
%s File's size in bytes.
%t File's last modification time in the format returned by the C 'ctime' function.
Are there any other options that can be used?
Existem. Veja o link para a página do manual.