Thanks - these brings back memories. The mill was starting to get shakey just at this time and the remaining slate roofs seen on Staff House and Cwrt in your photos would soon disappear.
In the first image, the building in the far right background was not a blacksmith's shop; it was the office prior to the large block just NW of the mill being built. After conversion to a house it was known as Cwrt, Welsh form of court, which referenced its 'count house' / office origins.
In the fifth image, the ruins in the foreground, downslope of the mill, had been the concentrate stores.
Images 8 and 9 show rails relating to Lefel y Ffordd which was located at the foot of the scoop into the tips shown in image 7; the rails lead across the road to the development rock tip associated with this level.
The barracks shown in images 10 and 11 had never been fully completed although they were about 60% useable; they were named Staff House.
I spent a lot of time at Cwmystwyth in the period these photos were taken but my photography was mostly limited to the underground - the surface buildings seemed unchanging and it was easy to mistakenly assume (as I did) that they would remain as they were indefinitely. So it was great to see your photos.