It is redundant to say or to write "and et cetera" (meaning: "and and so forth") since et means "and".
When speaking, the abbreviation, etc. is not pronounced by itself; instead, the full phrase is pronounced. One should say, et cetera (et SET uhr uh [English] or et KAY teh ruh [Latin]).
There is a quote from 1578 by a John Florio, who said, "The heaviest thing that is, is one Etcetera [sic]." It was considered the heaviest because it implied a number of unspecified things, too numerous to mention. Lawyers' etceteras [sic], in their bills of costs, were proverbial. The French had a saying, "Heaven protect us from a lawyer's etceteras [sic]." The same admonition could refer to misc. or "miscellaneous".
Beware of etc. because it can be the costliest item in an expense account. It is also considered to be a sign used in an effort to make others believe that someone knows more than he/she does in reality.
Used by more than a few
To make people think
They know more than they do.