Not sure about that parish transcription. From Genuki the parishes in the area:
"DEVYNNOCK, a parish in the hundred of Devynnock, in the county of Brecon, 7 miles S.W. of Brecknock. It is situated on the river Usk, and contains Ystradyelltey, Llanulid, Glyntawe, Llaniltid, Maescar, Glynn, and Senny. The great forest covers an area of 20,000 acres. The Roman road, Via Tulia, passed through the parish."
As you say, the spellings change a lot, often depending on whether the writer was Welsh or English.
I'm not sure about the name of his residence either. I'll check on the old maps and see if there are any clues.
Regards
GS