Gordo I am asked your question on a frequent basis usually followed by what do you use ? So second one first I use a "H" system Hasselblad with Phase One Digital back recognised as the best combination currently available, I also have several full "V" Hasselblad systems again coupled with Phase One backs - BUT it's horses for courses. Joe Public usually only sees sports photographers in action hence the long lense picture and the assumption that all Pros use Nikon & Canon.
I would definitely try to stretch to a DSLR as has been said it give you far more flexibility and you should find a wider range of lenses from a greater number of manufacturers if you buy Nikon.
Shooting in RAW files is a big advantage as the initial file size is smaller - good for storage - and can be converted into Jpegs, Tiffs, Giffs, Bmaps etc etc depending on what you are using the images for without loss of detail. Back up your RAW files onto DVD BEFORE you start working on them, then add the capture data. I then archive the DVDs and work on an external HDD.
Correcting imbalances such as colour temperature is a doddle in RAW format and can be done in batches. Incidentally I would recommend Capture One, Phase One's software which is also compatable with all the major camera brands.
Cameras are based on two different sensors CCD (Charge Coupled Device) and CMOS (Complimentary Metal Oxide Semi-conductor) the latter is relatively cheap to produce but gives a poorer image the former requires a sterile environment dust free etc is therefore more expensive but gives a far better image.
I wouldn't bother with UV, daylight or any other filter for that matter it only shoves the last element into the sun and causes potential flare - lense hood in place or not. I used to think it was important to protect the lense but that's just a filter company sales pitch.
if you take photos in low light you'll detect more artifacts, (Artifacts are small orange and yellow freckles in the dark)
This isn't true the "freckles" are digital noise, artifacts are OOF dust (usually) which has been picked up but the sensor often happening when lenses are frequently switched.
This was taken on the H2 & Phase One:
P.S. I hope that helps you a little.