Fascinating old techniques! You would want to keep the kit box in good shape to use it for construction

The magazine idea is still used and is a good way to spread weight.
The 2 stage gluing of the wing skin I believe was done due to the fast drying glue - similar to Ambroid, that would have most likely been used then. Although the 2 stage gluing is not really necessary with a slower drying glue such as PVA or Titebond, it could give you more control when attaching the top skin. However I would consider lining up the sheet at the LE and gluing it to the ribs and bottom sheeting only, first - holding it in place with masking tape strips with the wing weighted down flat on the board. When dry the top skin could then be glued to the ribs and weights (magazines - etc) and tape on the TE. You would need to be very careful to keep the wing flat any warp will be there forever. definitely don't do this on top of the kit box
The 1/4" wash in on the left wing is an interesting way to allow for the reduced lift on the inboard wing - assuming the model is flying in an anti clockwise direction. I would leave that out and build both wings flat and add a bit of tip weight to the bottom of the outboard(right wing). It would only need to be about 1/2 oz or so. The effect of the wash in will vary with speed where as the tip weight will not, and is the accepted approach now.
Good luck and Merry Christmas
John