verb contraction, etc., and so on

등등 or 등 is not really informal or colloquial in the Korean language, but "etc." and "and so on" are very much so in English.

Do NOT use "etc." or "and so on" in your formal essay. They make you look very lazy, vague, uncertain, and informal.

Using "such as" is a good way to be more specific. Take a look at the following example:

• The government is faced with difficult challenges, such as health care reform and the war in Iraq (o)
• The government is faced with difficult challenges like health care reform, the war in Iraq, and so on (x)
  

And do NOT contract your verb with an apostrophe in a formal essay. This also makes you look very lazy. You should spell it out.

• They don't, he doesn't, the government won't .... (x)
  
• They do not, he does not, the government will not .... (o)