Nut slot height

To cut nut slots I start by setting feeler gauges for the height of the 1st fret + , that seems pretty safe to avoid cutting too deep, and then I

That's a FLAT radius for a Strat! Think of it as an acoustic neck, then: verify whether the nut slot itself is flat or curved on the bottom

nut slot files Strictly speaking, a regular nut could be treated like a zero fret and the slots lowered to exactly the same height as the rest of the frets

nut slot depth You mean nut slots height ? With 3rd fret pressed, there should barely be any space over first fret Paper thin How to mark it ? The half