Just changed a couple of springs that were bought from Issunaz right pain fitting them seriously suggest getting your hands on a pair of coils spring clamps as they would have made life a hell of alot easier when fittting.
Not sure about this - I needed compressors when i changed mine but that's because I did not know how to release the brake pipes from the floor pan. If you can do this the job is pretty simple:
a) drop the exhaust off the rubber mounts but do not take off completely - support with wire NOTE: my exhaust was on its last legs and broke at this stage
b) undo four subframe mounts at the rear of the diff + unclip the ABS sensors. support the diff with a trolley jack
c) unclip the brake pipes from the floor pan
d) lower subframe and you are there!
If like me you could not free the brake pipes from the floor pan, you may need the compressors to squeeze an inch or two but that's about it.
There was a trail on this about a couple of weeks ago and someone kindly gave more info about freeing the brake pipes. Sorry can't help here as I didn't manage it