Your obd cinch socket 16 pin is under the ashtray in centre console
Depends on the model - for diesels its every 72000 miles but I'd recommend changing it at 54000 as I've heard some horror stories of cambelts breaking at between 64 - 72k
When you turn on the ignition the service indicator lights up, then press the reset button in the instrument until the mileage resets. This takes around 15 secs so be patient!
left hand side of the car,under glove box