Let's get input from several people on this including Bryan but one preliminary comment I would make is that I read Lucretius (and therefore presumably Epicurus) as using words that are translated as "soul" and "mind" and "spirit" somewhat interchangeably, so I would be cautious about dividing them up more specifically without very clear text references.
So, are our spiritual feelings innate Prolepsis of the gods, or just higher aspects our nervous system that we can attempt to control through breath work.
So as to this question I tend to think that anything regarding consciousness (which would include words like nervous system and mind and soul and spirit, and the processing work of the mind, including prolepses (which is related to images and how they over time shape our thoughts) is going to be generally considered to be a function of the soul/mind/spirit part of the body, but getting much more specific beyond that (especially "control through breath work") is going to be hard to do from the existing texts.
Bryan?