I'm a bit surprised to read your post:
In order for any of our venerable learned colleagues to offer any assistance they need an idea of what they are dealing with...
You haven't given any idea of miles already done, normal day to day use, operation of the vehicle or servicing history, these are factors that will determine the condition of your chariot and subsequently the suggestions from fellow forumites to cure your sick baby...
i.e: local short runs to school or shops is far worse than a gallop or two down the motorway: short runs don't allow the engine to get warm enough to get the cat in action to burn off any residual oil or fuel, don't forget that when the car gets 'warmed up' everything works smoother and as it was designed to do.
Also, don't forget that the harder you shove the 'go' pedal the more fuel you throw into the injectors = more fuel to burn on low or rising rpm whilst the turbo is spinning up = more **** being let out the back.
I'd be inclined to assume that you take good care of servicing (oil, diesel and air filters changed at regular intervals) so can only suggest that you may need to have your high pressure pump and injectors checked for both spray atomisation and pressure output.
If your HP pump or injectors are out of spec that can lead to poor spray patterns and poor burns, leading to sooty exhaust.
Your low water temperature is down to either lack of water (don't laugh, I've seen it) temp sensor or water pump shot.
This is all conjecture without any solid info from you. You have to help us to help you.
Cheers
George