Yep you get the silly clock. When I bought mine I asked if I could have the chrono function without the clock and was told firmly that I couldn't.
However Sports chrono is a bit of a marmite thing (love it or hate it) apart form the fact almost no one likes the silly dashboard clock.
The chrono function itself is interesting - stuff the time bit but the sports chrono also has the sports button that allows you to sharpen up the throttle response, the engine revs more easily it also backs off PSM's parameters to allow you a bit more freedom before the electronics interfere - having had it for 2 years I like it a lot. It does default the PASM to its harder setting but that is no use for roads just track work so most reset the PASM to normal with the sports mode on. PASM is standards on the CS (2 or 4) but not on the plain C2 (I'd get PASM on a C2 if I could but not everyone is a fan)
C2s or C4S over the stock C2/C4
PSE obviously is a must have (sports exhaust) and I really liked the Adaptive sports seats and regret not having optioned them on my car (I borrowed an OPC car for a long weekend loan it had the adaptive sports seats and I loved them). on long journey's I found them more comfortable than the standard seats and I am built like a fat Arnold Schwarzenegger [
]. The std seats have leather backs the sports seats have plastic backs.
Short Shift if you can get it - its a fantastic gear change and once you get sued to it the normal gear changes feels sloppy, indefinite and slow - which of course it isn't but thats how good the short shift is. The only two drawbacks are while very light when he oil is warm it can be a bit still in cold weather and also if your not used to such a definite gear box it takes a little while to get into it. along with the sports map on the engine its one of those options that makes the car feel more out and out sports car than a combined GT/Sports car
CD changer again is good, Cruise control is very useful if you do any long motorway schleps (it even gets better fuel economy than i can get with my right foot) and can be a license saver with all these 50mph roadworks piled with average speed cameras.
Finally if you like em sporty and you see one that spec suits otherwise go for an x51 pack (Powerkit) - it includes the PSE and gives the C2s?C4S an extra dose of grunt.
Others have covered the colours. If your planning on keeping it get any colour you like, except yellow of course - other owners will have to shoot you[
], you'll get wilder colours cheaper and loose more on them.