I have heard that male sperm swim faster and female sperm live longer, is this true?
There is some truth to this idea. There is a technique called "swim up" to help people have some control over the sex of their child, but it is not very effective (ratio from 50/50 to around 60/40 for males/females). It works like this: A sample of sperm cells is spun at a very high speed, which makes all the cells clump together at the bottom of the container. After the spinning is stopped, the sperm cells are allowed to swim freely again. The faster cells (the male sperm cells) swim up out of the clump faster than the female cells(generally) and are collected for use.
Another technique people try is timing sex with ovulation to influence the sex of their child. The arguement is that having sex soon after the woman has ovulated will increase the likelyhood that the faster male sperm will get to the egg first. Whereas sex slightly before ovulation male sperm will die off leaving only the female sperm around to fertilize the egg by the time it is ovulated. Once again, this technique isn't very effective.