I took this little excerpt from the linked page and had a good laugh. Just think if we could somehow figure out how to decode FM signals there could be a whole new world of interesting things to listen for.
No. The whole point of the circuit is that it has absolutely no selectivity.
(Well, technically the answer is yes. But it's a bit like saying you want a forklift instead of a car, and then asking "but how do I make it into a car". You're better off starting with a car. In this case you'd be better of starting with a conventional receiver -- one with a tuned front end.)
No, not unless you're talking about software defined radio. (And then the problem is simply shifted to different software modules rather than different circuits)
There's probably some ICs that will do what you want -- essentially they will have all the smarts to do multiple decodings, but still there are multiple modules in the IC, not just one.