Regarding pole reversal, there are lots of numbers involved and it can be difficult to determine what the numbers actually mean. For instance,
http://earthsci.org/education/teache...ec/platec.html this article on plate tectonics also talks about paleomagnetism, then further down under Sea Floor Spreading there is a diagram that shows that the current magnetic polarity has been like this for 300,000 years and the last time it was the opposite occurred 750,000 years ago - but stayed like that for 350,000 years. So if we look at 2.3 million years and take the number of polarity shifts in that time, we can come up with an average of around 300,000 years give or take. If our current polarity has been like this for 300,000 years - it just means that a reversal in the future is very likely. Current evidence suggests that this reversal is very unlikely to occur on a particular day, but more likely over a period of hundreds or thousands of years.
Now, what is more interesting is this article from ASNSW
http://www.asnsw.com/universe/altern...olarissima.asp that suggests that gamma ray bursts from Polarissima Australis in Octans coincides with our magnetic polarity reversals.
Most people say that magnetic pole reversal should not affect life as we know it, but what about the side effects?