I am surprised no one brought up Nikons 14-24 lens a stable mate of landscape photographers there is nothing to touch it on the canon side of things but maybe I am biased!
I don’t think the visible dust kit will do the job as it is a dry cleaner, Try to get a hold of some sensor swabs by Photographic solutions I use them all the time and find them excellant, I see you are in Rathoath there is a Nikon Repair centre in Summer Hill and they clean sensors for about 50 euros I think, I would be surpised if the sensor is damaged.
I have the D700 and just actually sold my D300s today, I bought the D300s to use as a holiday camrea along with an 18-200mm lens but I coul never go away without the D700. However I would wait a couple of months as there is a replacement due and you could either pick up a secondhand one cheaper or buy the new model. The only thing is be prepared to start forking out of some serious lenses!
You can set zoom etc, but on only on the flash, The EV can be set on the camera and in groups if you have more than one remote flash. There are plenty of youtube video demostrating how to use and setup Nikons system, do a search for Nikon CLS
Can i suggest you give black and white a go first of all, have a look on youtube for some video, try and keep the chemicals at the required temp including the stop, fixer and wash for practice.
I have used the Tetenal products for colour with ok results.