Since the OPs question is what happens AFTER the decay and all that stuff, I'd say:

In Islam teachings, you stay in your grave, untill the day of judgement, where everyone comes out from their graves, waiting for their turn in judgement.
Allah shows everybody he's judging a book where every single actions he made in his life is written, and then the judged go either to Hell or to Heaven, or if they're were an OK, but not so good person, they stay in Hell enough for their sins.

There's a whole lot more detail to this, and also, it may be very inaccurate, since it's written in Arabic and I had to translate it from my mind.

Extreme Coder