If I were in your situtuation, I would concentrate on suspension. The eibach's and koni's will work great. Also look into sway bars.

I think the 5zigen wheels look nice, but I don't think they come in sizes under 17". IMO 17's on a 5th gen with the eibach pro kit would look funny. I think you would be happier with 15's or 16's.

I probably wouldn't look in to the "go faster" mods if I were you. If I was driving that much a day, I would want the best fuel ecconomy I could have.

In addition to the timing belt and p/s belt, I think you should replace your water pump (at same time as timing belt), fuel filter, plugs, wires, cap, rotor, unless the previous owner told you when these were all replaced. I would also probably flush your fluids.