I use a WASD-moves-camera configuration, with the side buttons mapped to a-move+click and reverse-move+click. Really convenient once you get used to it. In any case, 4th and 5th buttons can be useful in many ways.
I don't think mouse is particularly important in CoH, as long as it's reliable. Find one you like and read the reviews from several sites. And stay away from Hama.
