1.) In "The Sacred Promise," Dr. Schwartz poses the very good question: How do we differentiate communications of external personalities from our own subconscious thoughts? For me, there are several clues... Do the ideas and images come from "out of the blue," in contrast to our accustomed observations, beliefs, and opinions, and are they salient to a significant problem or question? If so, it might be a good idea to examine them as possibly spirit-related. My hunch is that when those from the spirit world want to communicate specific ideas to the living, they do so by slipping the thoughts into our normal stream of consciously as unobtrusively as possible.
2.) The spirit world, in my experience, never tells me what choices to make, even when I repeatedly ask for such advice. However, I've received specific warnings about the consequences of certain choices.... And I do believe that we all receive such warnings, in some fashion or another, so that we can make informed choices.
(This is in contrast to much conservative religious teaching that states that "God" or some other spiritual authority orders or requires certain behaviors to fulfill some divine mandate.)
3.) Spirit communications in dreams are often expressed in emotionally significant and vivid visual images, rather than in words.