Don't bother!
The front ones are a pain to fit as you have to remove the wing liner before you drill the holes, and once fitted make it very difficult to clean the lenses properly, and the rear ones don't protect anything as they use the light mounting screws to hold themselves on
1 No they are 4x4 partly all the time, with a small amount of drive to the rear that increases when the VCU senses slip.
2 Correct.
3 Check the condition of the rear diff nose support. These fail and cause that noise.
The fluid is the only thing that can be changed in a VCU and The fluid is not available on the "open" market. There is a firm in Blackheath, West Mids that do a re-con unit.
BH, those rear pressures are way too high!!
Most tyre manufacturers say no more than 20% higher. Putting it up that high would suggest that you are possibly overloading the car.
It has been done by standard Freelanders and I believe the mad 2CV crowd.
In the late 60's and early 70's it used to be used as a "white" on road rallies anmd was thern done by Anglias and things!!
As has been said, you have the L series diesel. Excellent engine that will go on for ever if serviced properly.
Tyre pressures should be 30psi all round.
VCU support bearings are about £20 each. Replace both. Can be done in an afternoon at home. Buy proper ones and not pattern parts!!