my 2-bits worth
my 2-bits worth
Jetlag, FWIW if I know the size of the light the contractor is using, I put it so the center of the bulb is a little above head height, that is, about 74 inches above the deck. This allows the light to shine down slightly on the person standing at the door without being directly in their eyes, and looks nice in relationship to the top of the doorway. It's more a matter of personal prefrence I guess.
As to the stub outs, if the electrician knows that siding is going on the house he may be anticipating mounting some sort of block or box at the location of the light for the siding to butt into; I've used GC provided blocks of cedar that I put a 4 in. hole in and mount with a shallow 4/0 box and I've also used factory made plastic blocks to surround the metal junction box (I just try to remember to stub the NM into a hole in the box to one side, not dead center, because some lights may have a hollow mounting rod that is right in the center of the box, which creates potential for damaging my wires).
Or, the electrician may not care about junction boxes, and is planning on making up his wires in the canopy of the light...
I've done like you do on smooth outer surface like t-111 siding, I'll install a cut-in or I'll cut 4 in. or 3 in. hole in the siding put a metal 4-square box with a mud ring in the stud space. I put foil duct tape on the bare wood under the light canopy to comply with 410.23.