In my experience, by far the most common form in written language is etc. It is occasionally written in older texts as &c. (As Mike mentioned, &c. is basically the same as etc. after having gone through some typography changes.) I almost never see it written out as et cetera, and certainly not and cetera. Perhaps in legal documents it might be et cetera, but not general formal documents. In informal documents and speech, it would probably be better to use alternatives like "and more" or "and so on."
I think your question is about written English, given the mention of "&c.". But to be clear, in spoken English, it should always be pronounced as et cetera, and not contracted in some way.