14" wheels so GS-D2 which I can say suck donkey balls. See
here and
here for proof that the sidewalls are too soft. So yes ignore me if you like replacing prematurely unevenly worn tyres or even worse blowouts. I will not comment on GS-D3s as they are apparantly improved and lots of people I know who do hard driving have said they are fine, with a couple of people saying they are still to soft but that doesn't matter as you can't get them in 14" size anyway.
16k of aggressive driving? Hardly aggresive, mine lasted 5k iirc.
No, originals are Michelin pilot Sport SXs, now replaced with Pilot Exaltos.
When it comes to doing your brakes, cymattys setup is about the best you will get without changing caliper/disc size. Brembo Max front discs, brembo standard rear discs and Mintex 1144 pads. Fitting isn't hard, give it a go yourself. Also NGK plugs, castrol oil, citroen oem filters is the way to go.
When first purchasing the car I would replace the antiroll bar droplinks on any saxo, £12.75 + vat from GSF car parts and imo are a consumable part that should be replaced every 10k miles or so, stiffens up a soggy handling saxo no end and will stop any annoying knocking sounds.