The Land of Nurn
In response to #1...
I would hazard to guess that with any agriculture that was done in the fertile lands of the Nurn was done by subservient men and slaves, possibly rogue Easterling tribes or others from the east. I suppose if there were any peace loving Easterlings, Khandese, Haradrim types, the likely could have been sentenced to work the fields, and may have found that a better choice than being in the army.
As far as conditions in Nurn, it likely received a far amount of ash (hence the name Lithlad) from Mt Doom which likely enriched the soils. I suspect rainfall was pretty good being tht there are four rivers that fed the Sea of Nurnen. As far as sunlight, it may have gained some protection from the consistent ash clouds by the Ash Mountain spur that hooked southeast, then southwest that, along with a short eastern spur from Ephel Duaith, mostly enclosed the Plateau of Gorgoroth. Were the conditions great for growing crops and raising cattle? Probably not, but it is likely that it became quite good sometime after the war. There are no named towns in the area, but there would likely be small villages, camps etc. Just speculation on my part.
Annalist, Physician, & Historian
of The Black Company of the Dúnedain,
The Free Company of Arnor