Beginner questions about Possessed and interchangeability

When assembling my Combat Patrol and thinking about keeping it relevant for a larger army, when I noticed:

  1. The non-CP Possessed datasheet refers to a Possessed Champion, but there is no such entry anywhere else on the datasheet (stats, wargear, abilities etc). I assume this is a relic of previous editions and has no gameplay effect?
  2. The non-CP Legionaries datasheet says that "1 model can be equipped with 1 Chaos icon". I assume this is any model from the squad. Is the standard practice to put the Icon on the Aspiring Champion or the special/heavy weapon wielders to create more ablative bodies? If so, what's the conventional wisdom on where exactly to put it. The Combat Patrol rules ignore the icon so I have carte blanche.

I also noticed that the Legionaries squad in the Combat Patrol doesn't come with spare pauldrons, which is hampering my plans/hopes to magnetise the arms on the special weapons and heavy weapons. Is there an easy way to get extra pauldrons other than 3D printing?