I deleted the value . Should I delete this preference?

a. browser.contentHandlers.types.0.uri w/ Value = http://add.my.yahoo.com/rss?url=%s I can Modify to delete value. I learned that RSS was involved, but I do not know what the default should be. b1. browser.search.param.yahoo-fr w/ Value = moz35 b2. browser.search.param.yahoo-fr-cjkt w/ Value = moz35 b3. browser.search.param.yahoo-fr-ja w/ Value = mozff I see Mozilla and FF are involved, but why is Yahoo? Should I delete these 3 search preferences entirely? French and Jamaica involved? c1. extensions.universal_downloader.seopack.sesugg.fvd-gfloat-se-suggest-answers_yahoo_com . c2. extensions.universal_downloader.seopack.sesugg.fvd-gfloat-se-suggest--yahoo . There are 11 'more suggest' Values for these extensions were 'true'; I reset them to 'false'. What should I do now? d. yahoo.ytff.general.dontshowpoffer I deleted the value . Should I delete this preference? e. extensions.unversal_downloader.superfish_id with a five- part aplha-numberic Value. There are more; these caught my eye after I saw overt browser changes. Thanks again.