I really love what you're trying to do, but I'd be orders of magnitude more likely to make DuckDuckGo my home page and default search engines if (1) Wikipedia was before Google and Bing on your search failover links, and (2) those search failover links always appeared even for words in the dictionary (I still want the link to the dictionary)
The Firefox OptimizeGoogle (formerly CustomizeGoogle) extension used to allow you to set custom failover search engines, if you could edit a copy of the source code :D