[RoN_Rancor]

Well, remember, radio waves can only travel at the speed of light. It is likely that if we were to interscept a radio signal that it would have been floating around for hundreds or thousands of years if not more. Whether or not a species has better equipment than radio waves, it is still likely that at some point in their history that they used them. Also, there is no reason to believe that all Extraterrestrials are more advanced than us. Of course they would be if they actually traveled to earth, but unless they do, there is no way to know how advanced they are. You are right about radio contact being slim, but this is only because of the vast amount of locations to scan, huge amount of varying frequency, and of course the unimaginable distance between stars.

Yes, it is possible that life could form under different conditions. Since we can only observe one planet, we cannot neccessarily make figure out the characteristics needed for life anywhere. We can only base it on what life here requires. It is possible that there could be extraterrestrials based on something other than carbon. (I can't remember what it was called, but there is a substance that does pretty much the same thing as carbon that could possibly be used in its place.)