This post might be long and the TL:DR version is below. @Yskonyn
- There is no common format between RW and FG, I am copying only the necessary content
- Yes, I use RW exclusively as GM Campaign organizer during prep time and during session. More on that in the wall of text
Using RW as Campaign Organizer
I am GM-ins for many years and the problem for me was always the same - after the core book is released and available, the supplements and content books simply start to add up. I can’t carry all the books and I hate to use PDF documents during game. Searching for something is slow and when the data is all over the place - I hate this. I always wanted everything to be in one spot, organized in a neat way. I tested all from Scrivener, OneNote to The Keep and some online things, but neither had what I needed - no subscription based, no limits in what and how I put as content and the most precious - automatic link generation.
RW had it all and I immediately dropped all efforts to even write my own stuff. RW is now the main tool I use as Game Master. All systems that I plan to invest time and run games now get uploaded in RW. Depending on the game, it is either full upload of the book or partial, but everything is there. I organize the content in different ways, trying to follow the original books because it is much easy to navigate and search for something. Everything is nicely linked, structured and super easy to find during game. I no longer need to have notes or sticky notes. Finding what I need, especially in item/spells heavy system is now a breeze and I comfortably can allow all supplements in a game for the players to enjoy. Also speeds up the resolution time if some question occurs on rulings. Hyperlinks rule. 
During session (online or offline) RW is my game master screen and single thing I use. Because I have read the book once and then entered it into RW, I don’t need to really read all the stuffs during play, but simple look at the article and use the blue hyperlinks as visual cues to immediately know what has to happen here or what this rule or item is about. It is not replacement for a prep before a session - I browse what the plan is for today (if i use published content).
All notes I take during session I put into Notes articles and the plan for homebrew stuff I lay down in Storyboard articles. There I use different storyboards for the overall plot and for each story that unfolds. I also use the storyboard to make visual link between NPCs and PCs (unfortunately the feature is not that flexible, no way to have double arrows) and events and ever refer to articles/topcs in the world almanac where needed, though I don’t use it for the homebrew stuffs.
Moving Content to FG
Both tools are using XML standard for their database, but that is where the similarities end. The schema and the format of the data is so different that without converter is impossible to do it. I know the format FG is using, but reverse engineering of RW exports is something I don’t have much time to (becuase my motivation drops immediately and I don’t wanna sacrifice this time for something of dubious benefit, more on that below). Nowadays I put everything into RW and I copy-paste only what I need to FG. It is much faster than it sounds, because the actual heavy-lifting is done in Realm Works.
The adventures are prepared in convenient for copy-paste way - I try to adhere to the structure of the adventure and organize the content in the same way. Splitting chapter into scenes, events and other type of content. I avoid too much snippets, sections and sub-sections in RW articles, because this slows down copy-paste. I rather have 1 snippet that contain all and then I select all and copy to FG. This way the structure is kept and I have to just format the layout, something that takes few seconds at best (FG has shortucts, Ctrl+1-4 for styles).
I transfer only NPCs that I know will be used and don’t waste time to have monster manuals, encounters and such as module. The ruleset I use is community made (MoreCore) and I am using my custom module. I know that at some point something in the new version might break the things and investing time in something that might not be needed is not my way to go. FG is session manager and VTT for me, not organizer of any kind
Below are screenshots of the reference manual for Conan that I programmed for my players (I want them to have the best experience, I have FULL ref.man for Dark Heresy 2e… took me day of work but I love it). All links are draggable to character sheets.