] I understand that when Austen writes &c. that she means etc., as in et cetera but why does she write & instead of et?

I think, and I hope my dad has not failed me on this, that it is because in 'et' in Latin means 'and' in English. In the period of Austen's writing, Latin was still often learned by the middle classes and & is a sort of symbol meaning 'et'. Obviously, 'et cetera' is Latin for 'and so on' so the & was used in shorthand for et.

I hope that's clear enough!!

Elizabeth -x-