Theres a combined filler/level plug on the RH side of the transmission casing towards the back, near the transfer box (photo).
The fluid level must be set with the engine ticking over.
Only use Mobil LT71141 fluid (photo).
The fluid temperature should be between 30 and 50 deg. C when the level is set. Fluid temperature rises at about 10 deg. C per minute at tickover in neutral, so after around 4 minutes from starting from cold.
When the fluid is at the correct temperature (and with the engine running) move the gear selector lever from 'P' through all gear positions, pausing in each gear position for 3 seconds and then return to the 'P' position. Then, with the engine still running remove the filler plug and add/drain fluid until a small thread of fluid runs from the hole. Replace the plug & fully tighten to 35Nm (requires an 8mm hexagonal male wrench).
When you say trouble dropping into neutral what do you mean? Are you moving the selector lever to neutral but the car still drives?