Georgia Tech PhD funding question

[antonn]

Hello,
I'm from Israel and I'm trying to understand how does the funding system works. 
I have been accepted for a Phd in Robotics and the admission letter did not mention any funding.
I have contacted the secretary at Georgia Tech and only became more confused.
I hope anyone can answer some of this questions.
1. Every professor has a research budget from which he pays his students GRA?
2. If I'm not promised a GRA from the faculty, can I receive It from a professor?
3. GRA are considered a job? Can I receive a GRA from a professor which is not my supervisor?
4. A professor can offer a GRA from external funds which he receives for his research?
5. GRA cover tuition or allow a Tuition waiver? If not, how do you get such a waiver?
6. Is in normal to not receive funding in the admission letter?
7. Is it likely for a first year Phd student to get a GRA?
8. Is it normal to not get a GRA and be made to pay for graduate school?
9. How you ask for a GRA? Just send an email to a random professor asking him if he needs an assistant?

I guess some of this question will sound bizarre, but graduate schools in EE in Israel are free and everyone gets a stipend.
I'm basically trying to understand if my offer is legitimate.

Edited February 19, 2016 by antonn