Earth's spin is due to asymmetry in the accretion of matter during planet formation. The dust and gas that would form the planet was orbiting the center of the nebula before either the sun or planets formed out of it; interstellar nebula begin rotating and flattening before they form a proto-star. If you could pop the sun out of existence, hydrothermal vents would continue feeding bacteria with absolutely no solar energy until the planet eventually shed too much its internal heat (from its initial formation, also not from the sun).

There is nuclear energy transformations inside planets that creates lots of energy:

http://physicsworld.com/cws/article/news/2011/jul/19/radioac...