Re: does the lack of satellites account for lengthy days?

I don't believe you can make any generalizations about a planet's day length and the presence or absence of satellites. Mars, for example, has no significant satellites but has a day length about the same as the Earth. The spin rate of any terrestrial planet is determined by a complex mix of factors, including its original angular velocity when formed, tidal effects, collision history, and various perturbations. Mercury is tidally locked in a 3:2 resonance with the Sun, which explains its long day. Venus has probably experienced significant atmospheric tides (due to its very dense atmosphere) which have reduced its rotational velocity, and also experienced gravitational perturbations leading to a chaotic shift in obliquity (Venus has a retrograde rotation). The rotation rate of Earth is actually decreasing because of tidal friction from the Moon. An Earth day was only 22 hours long during the Cambrian, about 600 million years ago.

Some useful references:

• Tidal acceleration, describing the effect of the Moon on the Earth, http://en.wikipedia.org/wiki/Tidal_acceleration
• A mathematically intense, very interesting paper describing the evolution of Venus's orbit, http://www.imcce.fr/Equipes/ASD/preprints/prep.2002/venus1.2002.pdf