I also recommend the carbon blades with 32 teeth/inch. It´s easier to handle. The bi-metal blades last longer in normal use, but with a small piece for infrequent use you won´t have a real benefit.
When you sharpen the blade for cutting, it´s best to take one of the ends. Make sure that the teeth point to the sharpened end. That way you can push for cutting. I don´t recommend to sharpen the long edge oposite to the teeth. That would be begging for nasty cuts in your fingers.