I suggest you read the most awesome FAQ I've ever read, written by Apollo, it's the GHB/1,4.b/GBL FAQ sitting in Australian Drug Discussion, and the FAQ's home. It has the answers you're looking for, in terms of safety, effects and dosages.
If you're looking for information on GHB, I suggest you search your regional drug forums as well as drug basics for information.
to start you off. Unfortunately, being that this is posted in trip reports, I have to close it, as it violates our forum guidelines. Also, if I move this to another forum, they'll just ask you to use the search function, there are so many threads and so much GHB information around bluelight, search and you shall recieve