I have read that article on digg like week ago and now cannot find it. But here you have number 160 billion without "rogue" planets
http://www.huliq.com/12092/planet-co...ay-study-finds
Funny part is that life can probably be also on moons of big planets as it now looks more likely to find life on such moon in our solar system then on Mars. This would make the number of possible places where life can be even much much higher. Well, in contrary it is hard to imagine there could be life on those rogue planets somewhere deep in space without any light.
And yes, breeding is after our genome was decoded pretty stupid, since we now can see very well deep in our genetic history.
I just believe they have been here and humans at least saw their machines, for this I think is enough evidence, to say if their interfered somehow we really do not have any evidence if I know. It is also true that no one still explained how Piri Reis map was created, or how those ancient civilizations moved blocks of stone so heavy we still have no machinery that could move them in one piece even today. Maybe aliens were involved maybe not, but the truth is that modern human is 120 000-80 000 years old race. We know really well only last 1100 years, then Roman era, Egypt and little about some more civilizations in recent 5-10 000 years, but the rest of this time is still pretty big mystery for us.