I believe the 80A is a tungsten balancing filter. One of the real benefits of digital is white balance. That feature means you'll never have to use a filter for color balancing again. I agree that a polarizer is a must. I use mine for adding contrast and color saturation as well as for reducing light on a bright day. A polarizer can be used in place of a ND filter.

There are lots of opinions on protective filters. I generally use them. Some photojournalists use them instead of lens caps so that they can always be ready to shoot. Other photographers believe they degrade image quality too mcuh and don't use them. I usually buy the best ones I can get (usually B+W). That way at least I know I'm not putting crappy glass in front of good glass.