1) There were some odd answers. Although what Plato wrote of Atlantis is more than we have from any of his contemporaries, he is *not* the only one to mention it. Plato simply provides some actual information, rather than simply referring to it. According to him, it lay beyond the "Pillars of Hercules". This means that it could be *anywhere* outside of the Mediterranean.
Many believe that Plato learned details of Atlantis from some Egyptian manuscript. If he did, we no longer have any copy of that source.
2) There is no way of knowing what language they may have spoken.
3) It is certainly possible that some Atlanteans escaped the deluge, were absent when the deluge struck, or had descendants living in other locations, especially considering Plato's claim that parts of Africa and Europe were at one time under their control.
4) There is no indication that Atlanteans were anything other than human. Their physical characteristics are wholly unknown.
5) It is not possible to tell if "Atlantean" could have been a forebear of any modern language, as we have no known examples of it. Considering its reported time, it would predate the history of most known languages.
Note that many scholars believe that Plato just made it up, or that his facts were wrong. However, they are basing this theory on their own lack of knowledge. The *truth* is, it could very well have been based on historical record that has long since been destroyed. Possibilities: a civilization centered in western Africa, western Europe or the Americas. If trade existed between America and the Mediterranean in ancient times, it would explain the discovery of traces of cocaine in many Egyptian mummies. I do not believe that this is likely, but it is *certainly* possible. Likewise, an ancient (stone age) coastal sea-faring nation might be likely to leave little, if any, archaeological evidence in territory under their control, particularly if their rule consisted only of receiving slave tribute. It seems to me *very* likely that Plato was writing about a place that actually existed. Its location was, perhaps, not certain due to myths rising up around it over the *thousands* of years http://en.wikipedia.org/wiki/Atlantis , but there is no *good* reason to believe that it was not an actual civilization.
Another point: if scientists are correct about the extent of glaciers during the last ice age (about 10,000 years ago), and if they are also correct about how the melting of the much smaller remaining polar glaciers will flood coastal areas and islands, then it is no reach to believe that Atlantis was (mostly) submerged during the warming that occurred at the end of the last ice age.
Jim, http://www.jimpettis.com/wheel/