When and how do the wet ingredients get incorporated? The recipe mentions creating the well; should all of the buttermilk and oil be added? If not...

Looks as if it's been fixed. In Step 3, you add most of the buttermilk + oil, then in Step 4, you drizzle in the remainder, as needed. Lovely recipe!

Wow, that's a pretty big hole in the recipe- definitely best if you can get an answer from the author, but the recipe does ultimately require you to finish the dough by feel- if you have to, you could do something like 80% in the well and work up to the specification- "patchy and slightly tacky", I think it was.

I was going to suggest that you whisk the oil and buttermilk together and stir them in . . . but then saw the instruction to add some of reserved liquid. Let's hope the author of this weighs in, because you obviously will be stirring only a portion of the wet ingredients in at first. ;o)