Odds of intelligent life occuring?

[Gawdzilla Sama]

I'm probably speaking out of turn, I haven't read the whole thread yet, but I just wanted to address this:

1) The early earth has a massive collision with another huge arse planet thing. -extremely rare (considering the emptiness of space)

The era when this would have occurred was during the formation of the Solar System, when local debris was far more plentiful and collisions far less rare. Even now, collision events happen - just ask Jupiter. Gravity is still a major player.

The LATE HEAVY BOMBARDMENT got it's name from something, just can't recall what.