My advice would be:
If you want to increase the lift then do it right and get the correctly rate springs and shocks.
My view is that spacers are fine if you have a bit of a lean but not to lift the vehicle as you are using springs rated for a different application. Plus you can get a pair of rear springs for the price of a set of spacers.
You will need to do the front radius arms if you go more than +2" lift as the steering will be all over the place.
If you want to sort out the front prop then get a double cardan prop fitted, either a TD5 one with new front transfer box drive flange or get one made, there are places that will make you one to suit at about the same price as you can get the LR one.
Don't bother with the wide angle props, they vibrate the same as the standard ones do.
Rear prop should be fine, with regular greasing and U/Js in good nick. If you're fitting the cranked trailing arms then Scorpion Racing's ones are able to fit spacers to bring the rear axle back into line and stop any problems.
As for the shocker mounts, if you get the right shocks to suit the springs then you shouldn't need to lower the mounting. You can if you want a bit of extra droop but make sure your bumpstops are lowered to suit so you don't wreck the shocks.
Try a few searches as there are loads of threads in here about lifting mods for the Disco. :D