Shudder pulling away plus a clunky 1-2 shift on a 9G-Tronic at 75k km is very often a software adaptation or old fluid issue, not a failing gearbox. Ask for a scan of the transmission module and a fluid check before anyone talks about parts. A proper service with the correct ATF is cheap compared to a rebuild.

Spongy pedal plus grinding is two separate things. Grinding is pads or scored rotors, but a soft pedal points at old fluid or air in the lines, so ask whether they'll bleed the system with fresh fluid. Don't just accept a pads-only quote.

Depends entirely on the lift. A portable scissor lift gets the truck maybe 3 feet up, which is fine for the frame rails and exhaust but tight for anything around the transfer case. Ask them exactly what lift they bring before you book, because "portable lift" can mean a lot of things.

55D23L is the correct JIS format battery for a Nissan Patrol and Amaron units in this size come with terminals already configured for Japanese vehicles so no adapter or modification needed on your end.