I had a similar thought about the drilling xy - I was thinking of a block with two of its edges having "V" grooves at right angles - one to clamp to the leg, the other to guide the augur. Having said that, I'm more than happy with the result of careul sighting with square/sliding bevel.
Before weaving the seat I finished the wood. This stage presents a dilemma for me. I have left the finish straight from the skew chisel for the turned parts, and card scraper for the back legs, with a bit of burnishing with shavings. I could have sanded it smoother, but I worry that I will lose the greenwood character that way. I applied a thin coat of Danish oil with a cloth, then when that was dry, two coats of homemade wax polish (2:2:1 mix of beeswax from FIL's bees, natural turpentine, raw linseed).
The seat I wove using seagrass. No photos of the process because it is fairly straightforward, and being no weaver, that is good by me ! I made an error in estimating how much seagrass I would need, so the warp and weft are different batches, the weft being some left over from a stool. I have convinced myself that I like it that way and so it is a happy accident. Here's the fished seat:
And the finished chair:
Just an ash log, some seagrass cord, oil and wax. No glue, nails, tacks, sanding or power tools.
Thanks for watching - I hope you enjoyed a slightly different style of woodworrk, and thanks too for the kind/helpful comments