This thread covers the parts needed that mostly jive with your list, and I did a little checking as well. I think you're on the right track on all these:
Left radiator - 17117602241
M8-Z2 hex nut with plate - 07147144953 x2
Holder for additional radiator - 17217540030
M6X20-U2-8.8 Hex bolt - 07119903995
Hose from radiator bottom to thermostat - 17127602294
Hose from engine inlet to heater radiator - 64219222129
Hose clamp - 64216963248
The one I think you don't have correct is 51647154546 which is listed as Front Bumper Carrier Bracket - Right. The thread I linked above says the bracket you want is 51647154545, which comes up as Front Bumper Carrier Bracket - Left. Since the aux radiator is listed as "left radiator," that left bracket makes sense to me.
Also for ducting, if you're a coupe you have the option of deleting the fog lights with the 335is lower grilles:
Lower Bumper Grille - Left - 51118050585
Lower Bumper Grille - Right - 51118050586
The ducting behind these grilles, if you have an M Sport coupe, is already the same as the 335is.
For the sedan there's a Performance air duct which is 51742157678 for the standard bumper or 51742157680 for M Sport.
Here's the thing though, adding this aux radiator, even though it's OEM, is a lot more complicated than just replacing your radiator with a higher-capacity one. To me, the only reason I can think of that the aux radiator is part of the PPK because that way BMW can bolt on a bit more cooling capacity rather than swapping out a radiator for a higher-capacity one and then being left with having to dispose of the original radiator.
Anyway, this begs the question, sure the aux radiator is OEM, but why go for all this added complexity when you could just pick up a higher-capacity radiator that will drop in place of your main radiator and give you the cooling capacity you need? The CSF radiator is only $439 from Top Gear Solutions.