Can I just point out that exobiology is actually a valid branch of science; in fact NASA and ESA spend considerable monies on exobiology.
Unfortunately exobiological predictions do require a lot of knowledge from various fields (atronomy, geology, organic chemistry, inorganic chemistry, genetics, ecology, energetics.... it goes on) but there is plenty of material available on the web.
This is not the "random speculation" forum. We have one of those, located here: http://www.scienceforums.net/forums/forumdisplay.php?forumid=59