Jody has been using a MacBook Pro as his main computer and recently moved over to a MacBook Pro. But he hasn't been able to move his Firefox extensions and bookmarks over. How can he do it? Leo says that Firefox has a sync capability at the bottom of the WIndow. Set up the account and Firefox will sync from one machine to another. Easy Peasy. The other way to do it is to export bookmarks through the Bookmark Manager.
Preferences are stored in the Application Support of the User folder. One is in the home directory (which Apple hides). In the system library folder as well. Check out this technote from Mozilla - https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data
But Sync is the easiest way to do it.