Since version 3, Firefox stores bookmarks in a SQLite database instead of a static HTML file. You can export your bookmarks to an HTML file, but I don't know whether you can automate that. To export manually, see: Export Firefox bookmarks to an HTML file to back up or transfer bookmarks.

Have you considered the Bookmarks Sidebar? You can open and close it using Ctrl+b. Not full screen, but if you use about:blank as your home page to avoid distractions, perhaps sufficient for the job?

Or there might be an add-on that displays bookmarks full screen as a page.

Type about:config in the URL bar and hit Enter.
If you see the warning, you can confirm that you want to access that page.

browser.bookmarks.autoExportHTML = double-click to toggle to true

Then set the bookmarks.html file in your Profile as your homepage.

See also:

• http://kb.mozillazine.org/Export_bookmarks

Quote:

Note: In Firefox 3 and above, you can automatically export your bookmarks at exit to the Firefox profile folder "bookmarks.html" file by setting browser.bookmarks.autoExportHTML to true in about:config but this may delay browser shutdown if you have many bookmarks. [1] You can set the name and location of that HTML backup via the preference browser.bookmarks.file. [2] Retrieved from "http://kb.mozillazine.org/Export_bookmarks"

The ed-meister got it right. But I'm going to repeat what he said, and add a few lines, for the other newbies (like me) who need things spelled out, step by step.

type about:config in the URL window, and hit return

       (if Firefox puts a 'www' in front of about.config,  Look again,  you 
       want a colon, not a period)

a warning will come up, "This might void your warranty!" click I'll be careful, I promise! in the Filter: window near the top type in bookmarks right click on the line browser.bookmarks.autoExportHTML click on Toggle. Under 'Value' it should now read 'true' Exit Firefox

  From now on every time you exit Firefox, your bookmarks will be written to: 

/YOUR_HOME/.mozilla/firefox/YOUR_PROFILE_DIR/bookmarks.html

  Note:   bookmarks.html  won't exist until you do this the first time.

Restart Firefox Click on Edit

  Click on Preferences
      Go to the General tab
        Enter the entire path and   /bookmarks.html

(I like to do by surfing to that page in the URL window. Say, start by typing in /home then hitting return, then further drilling down to the bookmarks.html file one directory at a time, by clicking on the next directory.) When you click on bookmarks.html, your bookmarks will open as a web page. Then you can click on 'Use Current Pages' on the General tab.

Note: the bookmarks that you can see by going to your home page will only be changed when you exit Firefox. Sooner or later you'll save a bookmark, then go to 'home', and the new bookmark won't be there. You'll think, this isn't working. But it is, you have to exit Firefox for that bookmarks file to be updated. I don't know of any way to update the bookmarks.html file, and then reread the bookmarks file.