Yes, "crossdreamer" is a term coined by Jack that refers to transgender people who "dream about being ones target sex or get aroused by the idea of being ones target sex." (Borrowed from his book, A "Creative Crossdreamer Vocabulary: Reflections on Transgender" which is available for Kindle at $2.50. I recommend it!)
I think it's safe to say that all TG people are crossdreamers (at least for the dreaming aspects of it) but not all crossdreamers are, for example, crossdressers or move toward or consummate aspects of transitioning. For example in my case I am undeniably transgender, am a crossdreamer, an occasional crossdresser, and at least for now have no plans/intentions to transition.
As Jack wrote, please feel free to write whatever comes to mind. I think the book will be important in offering readers with more personal stories about their experiences, desires, and needs w.r.t. what it means for them to be TG and crossdreamers. I think it will be a valued addition to biographies and other books.