startpageのパラメータ調べてみた。
Firefoxのkeyword.URLに設定する場合の参考になれば。
wikiに乗せるとかは任せる。

括弧内は MY SETTING の項目
https://startpage.com/do/search?
&ssl=[0|1] (Secure Socket Layer (SSL) / HTTPS: 1=Enalbe)
&font_size=[small|medium|large] (Font Size)
&recent_results_filter=[0|1|2] (Date filter: 0=Disabled, 1=Enabled - Open, 2=Enabled - Closed)
&language_ui=[english] (Interface language)
&disable_open_in_new_window=[0|1] (Open search result in a new window: 0=Enable)
&disable_family_filter=[0|1] (Web/picture family filter: 0=Filter all results, 1=Do not filter my results)
&num_of_results=[10|20|50|100] (Results per page)
&picture_privacy=[on|off] (Anonymous Picture/Video Search)
&language=[english] (Search language)
&disable_video_family_filter=[0|1] (Video family filter: 0=Enable)
&suggestions=[0|1] (Search Suggestions: 0=Off, 1=On)
&query=検索文字列

例 エロフィルターなし100件表示で"てすと"を検索
https://startpage.com/do/search?&recent_results_filter=0&disable_family_filter=1&num_of_results=100&picture_privacy=on&disable_video_family_filter=1&query=てすと