I had a chance to wedge and assemble the chair this morning. There isn't a lot of glue used here. Most of the tenons are wedged. I've always pre-sawn the kerf when making wedged tenons in the past. But Buchanan's method is more elegant: He just cuts the tenon a little proud of the mortise, and then splits it with a chisel. It's so quick and easier to align.
I tried like heck to finish turn the spindles with the skew, but I think I may still have to use some sandpaper.
I had amazing success reducing vibration by turning with a drill chuck in the tailstock. It captures the end without providing any longitudinal compression. That, and my fingers as a steady really gave better results.
I made a mistake on Spindle 5: I had not seated it fully before cutting it to length. So, when I hammered the wedge, the top went below the surface. I should have used an end-grain plug. Didn't think about that until too late. This is all going to be painted anyway