I've never found a service manual for the Terrano. But one of the guys (pretty sure it was Ekim Naelcm) on the FB page made an R50 auto trans work in his Terrano, and IIRC all it took was swapping over the bellhousing and having a torque converter made, which means it's (at least a variant of) the same RE4R01A that's in the North America-spec gas-engine trucks.
The '95 US manual specs 8.5 liters (9 US quarts) for the 4WD, 7.9 (8-3/8) for the 2WD. It calls for "Genuine Nissan ATF" or Dexron II. The R50 (which has an upgraded variant of the same slushbox) service manuals spec Nissan Matic D, so I assume that's what "Genuine Nissan ATF" means. I used bottom-shelf generic dex-merc in mine and it didn't seem to mind.
I flushed mine by putting the cooler lines in a bucket, running the engine until it stopped pumping brown fluid into the bucket, adding fresh fluid through the dipstick tube, and repeating that process until the fluid coming out was recognizable as the fluid I was putting in. Dropping the pan looked like a PITA, and I'd been told that the filter is more of a screen than a filter anyway, so I didn't bother with it. I have since seen a picture of a trans filter full of what looked like clutch material--not sure what else was wrong with that transmission, or how common that is. Might be worth checking the filter (and wiping the sludge out of the pan) for peace of mind if nothing else.
Be careful filling the transmission. The level changes a lot as it warms up, and you're supposed to check with it warm. I thought I had it close, warmed it up, and had to drain about a quart to get it back down to the mark.