Being of two minds

I've been trying to find the time lately to read up on a few different, related topics:

a.    Karl Popper's (now little discussed) idea of 3 Worlds (discussed with John Eccles in a book from the 1970's that I stumbled across somewhere in the 70's or 80's);  

b.   the fact that I find it hard to stop puzzling about how, in terms of the question of free will, and consciousness generally, an idea planted into a mind from outside of it (via language, or visual art, or music) can have consequences for how a person thinks, feels and acts.  (Basically, how does something nebulous from World 3 cause an effect in World 2 and 1?);

c.    how the idea of Buddhist inspired mindfulness fits into this, and what exactly is doing the observing of the rest of the mind if you undertake meditation for the purpose of watching the flow of thoughts through the mind?  (Oddly enough, there is a decent blog post on this topic called "You have two minds, and here's how to use them" by the guy who wrote the self help book with the crude title.)   The basic idea is that we have an "observing mind" and a "thinking mind".   But I have not had enough time yet to read up in much detail on different Buddhist schools' thoughts on how this works.  

d.   my feeling that this should all be significant to the recent topic of sexuality and gender, which is all based on having a core that cannot be changed, and must be fulfilled.  This is often brought up by the anti trans (so to speak) side of the culture wars - that the idea of have a male or female soul in the wrong body is a bit of mysticism which the otherwise irreligious liberal is often happy to subscribe to.  In any event, given that regardless of whether it is innate or not, transgenderism is a lot harder to accommodate (in terms of the effort that has to be put in by most to appear as an attractive member of the opposite gender) than accepting people can go to bed with whoever they want, isn't it worth teaching mindfulness to those who might be well served  by merely observing their passing and intrusive feelings about their body rather than being in a hurry to modifying the body to match?  But any article that I read about it seems to be from the perspective of using mindfulness to affirm that the "wrong gender" feeling is OK (and to be acted upon.)