My serpentine belt is cracked, is this something easy to replace myself? And how important is the belt?
Yes, you can replace it yourself. You will need a serpentine belt tool to relieve the tension on the belt. Do not cut the belt. The new one might not be the right size and you may need to exchange it. Once the old one is off, you can put the new one on. There is a diagram on the radiator frame that shows how to thread the belt. Use the belt tool to shorten the belt route just as you did to remove the old one.
BTW, just because it’s cracked doesn’t mean it needs to be replaced. But if it has not been replaced before, now is a good time. It has stretched a lot and that could mean it needs replacement.