I can think of a few ways to enter any entire document into Freeplane. I did the Core Book the hard and simple way, with lots of copy-and-paste. It required more work and time than thought. The longer explanation that follows also appears in the Workflow topic of the Eclipse-Phase-Mind-Maps wiki on GitHub. I'll update that as I work. Feel free to refer to and to contribute to it. This workflow description omits minor items such as "Styles" and an explanation for the metadata branch. It also assumes you know what Freeplane means by "Node," "child," "branch," "Attribute," and "Notes." This workflow description also omits any description of how to use git.

1. I opened the PDF, selected all the text of the Table of Contents, and copied it to the clipboard.
2. I opened a new map in Freeplane. In it I made a new node with the title "IMPORT". I made a child Node of "IMPORT", which I titled "Core Book".
3. I pasted the clipboard's contents into the Note Window of the node "Core Book".
4. For each of the chapters of the Core Book, I made a new Node. At each new Node, I cut the chapter's title from the "Core Book" and pasted it into the Node's title.
5. For each subsection of each chapter of the Core Book, I made a new Node entry beneath the appropriate Node. At each new Node, I cut the subsection's title from the "Core Book" Node's Note Window and pasted it into the appropriate Node's title.
6. I repeated step five until I had completely reconstructed the Core Book's Table of Contents. Each Core Book chapter became a branch of the mind map. Each line entry in the Table of Contents became a Node of the mind map. This took a long time.
7. For each Node of the mind map, I copied-and-pasted the text from the corresponding section of the Core Book PDF into the Node's Note window. This took a longer time than step six.
8. You can filter, search, and select by Attribute in Freeplane. I opened the Attribute Manager and created an Attribute named "status" with the values "corrected", "raw", and "proofed". I then created an Attribute "origin" with the values "Core Book", "Gatecrashing", "Sunward", and "Jay Dugger". These two attributes tag Nodes according to whether they've just been imported, had a single editing pass, or been proofread, and by their source in a rule book or from a particular person.
9. I selected all Nodes of the mind map, deselected the branch titled "IMPORT", and assigned all the selected Nodes the attribute "status" with value "raw" and the attribute "origin" with value "Core Book". This marks all material in the mind map just imported sans editing from the Core Book as such.
10. I deselected all Nodes of the mind map, selected the branch title "IMPORT", and assigned all the selected Nodes the attribute "origin" with value "Jay Dugger". This marks all material in the mind map that I made as such.
11. I started correcting the raw import of each Node's Notes by reading the Note text, correcting line breaks and copy-paste errors as I went. This means I had a copy of the Eclipse Phase rulebook open in one window with the mind map open in an adjacent window. After I corrected a Node's Notes, I changed that Node's status attribute from "raw" to "corrected".