These settings in about:config might have some security/privacy related affect, but information about them is not that easily available:

• security.ssl.false_start.require-npn
• geo.wifi.uri
• browser.formfill.saveHttpsForms
• breakpad.reportURL (should we set this to ""?)
• extensions.blocklist.level
• network.stricttransportsecurity.preloadlist (quite self-explanatory, but needs reference)

See also:

• Replaced a few TODOs by the variables they were refering to, updated the README #6