Hey everyone, nice Cafe you've got here lots of nice people

. Well basically I have one question, which seems to be a dificult one since no one has been able to give me a straight answer. I'm sure an idea will pop up here. I'm a student who came in as a tourist and I would like to change my status or get some kind of DNI, or NIE in this case I suppose. If I'm already in Spain, what can I do to get this done? or is there any other way around it? I had heard something about the Comisaria being able to extend your stay with enough proof you can actually afford it and have a good reason, how true is that?
It's a real mess having to back to the US and wait all that time. What exactly happens when you over stay and re-enter the US, do THEY bother you or does the Spanish authorities question you when you are leaving? Anyways thanks once again, I could really use the help. Hasta luego!.
SK