It's a personal thing, I'd rather clamber over a few boulders than walk down a really steep slope, it hurts my knees less!
No, my description aims to describe the former. The stile is 'where the 1:25k map states '610' on the contours, and that's at the grid ref. you state (ish).
We're at this point in the 13th photo in my report.
Again, this is a preference to avoid the steep ground of Cwms Hetiau and Glas Bach. As you say, there's about 200 yrds on the road before you get to Nant Peris car park.