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.
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Welcome to ELL. I think a variation of this question would be more popular on EL&U. Voting to close as (in it's current format) this is opinion based and therefore not suitable for SE. In my BrE opinion, although understandable, I would assume you do not know the English language well as you are mixing two languages together. I would recommend you stick to saying "et cetera" or use the full English version "and so forth" / "and so on".
– Bee – 2019-11-14T12:41:29.6602
I'm sure most people would understand your usage - but it would stick out a mile, since no one else does this. Just stick with the standard forms.
– FumbleFingers Reinstate Monica – 2019-11-14T12:42:17.870Apologies. Did intend to post on EL&U not on this site that I've never been to before. – MXMLLN – 2019-11-14T16:14:30.580
Arbitrarily changed the question from "understandability" to "correctness". Most of the answers on English.SE say "the choice is stylistic", so used more ambiguous wording in my question. SE's brilliant policy banning opinion-based questions is far less relevant here. – MXMLLN – 2019-11-15T07:52:50.053