Does the wearing of armor preclude one from wearing anything in either their body or chest slots? In other words, could one wear a mantle, shirt or vest (chest slot) under one's armor, with a robe or vestment (body slot) over the armor and then a cape or cloak draped over that (shoulders slot)?
As long as i understood the rules,a PC can wear an armor (armor slot), a mantle (shoulders slot) a robe/clothing (body slot).
Edit: forgot the chest slot.By RAW, it can be equipped as well w/the other items (armor and mantle and robes)
Actually a mantle is chest slot. You can have a cloak (shoulder slot, a mantle (chest slot), a robe (body slot) and armor.
look there and scroll down to the 'Magic Items on the Body' section. each of those slots can have an item of the appropriate type.
armor, body, chest, and shoulders are 4 different slots each capable of wearing a magic item.