Soofie,
This might help you a little bit.
It seems that Castleton Mill still exists, just off what is now Armley Old Road (the bit they chopped off when they built the Armley Giratory).
There appears to have been a Castleton Road and a Castleton Terrace nearby, but I'm not quite sure where.
There is also a Castleton School, a new building a short distance away on Green Lane.
Now, my memory might be playing me tricks (it's many years ago) but I thought the school on Armley Road (known locally as "The Clock School" because of its clock tower) was Castleton School, and the original school on Green Lane was Green Lane School. The Clock School is still there, but I think it's offices now.
Also, see the topic in this forum "Ellis in Yorkshire 1880s" if you haven't already read it.
Hope this helps,
Jon