yup, it might just need a simple tweak of the shift rods to get low range back. or the bushings might be shot. or rust is allowing too much flex in the system. or something inside is broken. (but that's less likely)
after that, check the link in my signature for a how-to for bypassing the CAD in the front axle.
If you're referring to the knob, it's a random generic from like autozone, purchased many moons ago.
If you're referring to the shifter itself, it's from a TJ.
the advantages are theoretical. Higher pressure lets you run a higher temperature and a higher temperature allows for better efficiency. Lots of different cars have a pressurized system.
and don't forget to be proactive and run through all of Cruiser's MJ tips. it covers all the more common wiring issues. link is in the link in my signature.
the factory bench leaves much to be desired, especially if it's one without headrests. But if we're talking a swapped-in bench like the late 90s Dakota, then I'm all in.
But then again, MJ buckets are incredibly comfortable to me personally.