Welcome to GTP, Mercedes CLK. There is a search function at the top of every page. If you typed "24 hour races" into it, you'd get some results. Plus, there is a B-spec function for long enduros. But it has been done before in a-spec, by using something called the pause button.
Loads of us. There's tonnes of reports in the race reports section from people who've raced the full 24hrs, in many races.
Done 7 of them myself.
Anyway, it's not really new news that people find this strange. Suggest a search for "24 hours" would find you various threads that discuss the pros and cons of 24 hour races.
Since it's been done to death in the 4 years that GT4 has be around though, there's little merit in keeping another "moaning" thread open.