Hi Rob, I'll take a shot at your questions.
When drafting the BB threads, the person writing them has to find the best (or quickest) photos or youtube videos that get the idea across. So while it might show things that don't match the requirements, the general idea is what we're usually after.
From the Dimensional Lumber Woodworking Badge (which is the parent badge to this BB):
Projects involve dimensional lumber, either from a sawmill or purchased. No plywood, waferboard or particle board. Includes construction, cabinetry and fine woodworking.
Power tools, nails, screws are used, but hopefully less than in most construction. A little more emphasis on good joinery.
Much less glue than most construction these days.
No paint. possibly some tung oil or linseed oil - but just a little. A lot of emphasis on untreated wood.
1) Our "target" for this is probably a piece of furniture made 200 years ago in a utility woodworking shop - not for a castle or what would become a $100,000 antique today.
2) Some pocket screws are probably reasonable but not the whole thing held together with them. The "man-made materials" it's talking about is OSB, plywood, waferboard and other wood-like substitutes.
3) Some protection is fine but we're after healthy-to-apply ones. So some oils would probably be called for. I'm guessing a homemade natural paint would be just fine.
4) I suspect drawer slides slide through the current requirements. But I'm guessing the hope would be that you'd have the drawers undersized from the face frame slightly and sliding on the dust frames with maybe a bit of beeswax or other wax lubricant. I'm guessing that, or something similar, is what they did in the olden days before drawer slides.
Hopefully that made it a bit clearer?