user_pref("browser.urlbar.suggest.engines", false);
user_pref("browser.urlbar.suggest.importantDates", false);
user_pref("browser.urlbar.suggest.mdn", false);
user_pref("browser.urlbar.suggest.quicksuggest", false);
user_pref("browser.urlbar.suggest.quicksuggest.nonsponsored", false);
user_pref("browser.urlbar.suggest.quicksuggest.sponsored", false);
user_pref("browser.urlbar.suggest.recentsearches", false);
user_pref("browser.urlbar.suggest.searches", false);
user_pref("browser.urlbar.suggest.sports", false);
user_pref("browser.urlbar.suggest.topsites", false);
user_pref("browser.urlbar.suggest.trending", false);
user_pref("browser.urlbar.suggest.weather", false);
user_pref("browser.urlbar.suggest.yelp", false);
user_pref("browser.urlbar.suggest.yelpRealtime", false);
Updates: there is a policies.js option that allows one to take control of updates.
"DisableAppUpdate": true,
On Linux, placed into /usr/lib/firefox/distribution/policies.json