I haven't read this whole thread (first two pages, yes). So I maybe repeating what someone said.

back in the day, there was a plugin that you could lease for $99 a month a put in your members area. For all practical purposes it was a "search the usenet" plugin.

Now,

There is an extension that you can put in firefox that does what you want to do - type in keywords and it searches all those places.

Here is one thing that I don't like about your idea. Forget copyright for a second. Let's look at CP. Do you have a way of filtering out links to CP? Those places are loaded with it.

I have an idea for a torrent site that is much different than yours and is perfectly legal.