if you have a look again check 2 small things:
1.) I'm pretty sure the rear light clusters are not discoloured, they are not the same as the 156. Have a look at a few pics on the net, just to confirm it's ok
2.) If you are worried about the missing letters, don't, a lot of people removed it to have a cleaner look. I - on the other hand - like to shout into the face of the Prius owners what I drive. Pathetic, but extremely satisfying
If still not convinced, then check for colour differences between the boot and the wheelarches (on both side), you'll spot the differences, this colour is very very hard to match. If you have CDO* like me, you can check if the two bumpstops of the boot are the same, and if the little sticker with the colour code is still on the inside of the bootlid.
The code for the ICS will set you back about ~100 euros, so try to get those as part of the deal. But before you do check for the card either in the manual/service history book, or in the boot above the battery, mine was in a plastic bag taped to the top of the SatNav.
The 166 is very comfortable to drive, the memory seats (with 3 programmable slots) making a 1000+ km run across the continent a pleasure.
You can also do an ECU reset, so the gearbox ecu learns your driving style.
Unfortunately the Heater matrix is the weak point of the Sportronic box. Open the padded cover at the passenger footwell, and check for moisture. The gearbox ecu is right under the heater matrix, and a leak can destroy it. A lot of us wrapped the ecu in a plastic bag to avoid this.
Check if the CD changer is working, and if you have a new disc for the satnav. Also, check if you have an extra black box over the CD changer in the boot, that's the DSP amp, a nice addition to the car.
good luck! it's a very nice colour, you'll like it
*CDO is OCD, but the letters in the correct order