Re: No Moon
As per psychotick, the moon keeps your planet spinning on a steady axis which is important to evolution. No moon and the planet will change axis more often, Earth does even with a moon.
I also think tides will have mixed things up a bit and may have been important for life to begin, no moon, no tides.
You would still have seasons as they are mainly driven along by the axis of the planet.
To be honest however, if I were reading a book I don't think a missing moon would bother me too much and the visual difference would be interesting, even after all the above!