The Housed Stringer How to build stairs 

I found a lot of his stuff in Fine Woodworking magazines/books.

Why not just make 1 jig your self And use a 3 1/4 HP router with a 7 degrees dovetail routing but. Using a collar at the base of the router? I made my first jig 30 years ago and fine tuned. Till I was able to buy a vintage Rockwell/Porter Cable 521 template. Check my channel I have a small video clip of 1 of my templates.

The wedges are what fixes them tight, otherwise they would move around and fall out - wedges are used to prevent creaking. The wedges should not go all of the way into the the corner where the tread and riser meet though, he has that wrong - that will cause creaking

Wood shrinks then the treads squeak. Glued in wedges stop that for a few decades.

I do atleast 1/4 inch but that's on a 1 1/2 stringer. If your stringer is 2inch you could do a little but more

Paint grade 5/4x12 poplar is nice