There is a small search box in the upper-right corner of the screen, with the gray word search in it. Just type what you are looking for into the search box and press the Enter key. See Wikipedia:Searching for more details.
Cite it as you would any other web page in accordance with the normal citation practice the publication you are submitting the paper to follows. Citing the individual authors is not necessary, but you should at least include the date on which you retrieved the article (and ideally the full timestamp from the history).
Automatically generated citations in several standard styles are available through the "Cite this article" link in the toolbox.
You should correct it. (See Wikipedia:Contributing FAQ.) Wikipedia is written by volunteers who believe knowledge should be free for everyone, and the community is always ready to welcome new volunteers.
Because Wikipedia is an all-volunteer project that anyone can edit, errors or omissions can and do creep in. This should be kept in mind when reading; the very nature of Wikipedia means it should not be trusted completely. Articles frequently contain citations of authoritative works where a reader can verify the information found.