My 11 year old son and I live in GA. His biological father lives in FL. We have joint custody and his wages were garnished for child support. He has not contacted my son since May 2005 and he lost his job in July 2007 so we haven't had a check from him for 8 months. What rights do I have? Can I change his last name without his father's consent? Can he be adopted without his father's consent? Is there a timeframe that establishes abandonment? If I were to become deceased, I would like to protect my son from being automatically sent to him to live. How do I accomplish this?

First, you need to go back to court to get some support again. Depending on how high of an unemployment rate and what not is in the area your ex lives in and how steady his payments were before losing his job the judge could order a few different things. Around me I have mostly seen the judge give the man a paper that has to be signed by all the "head hunting companies", places people go to have them find them a job. That way he can show an honest effort at finding a job. If he gets placed somewhere then they can continue garnishing his pay.
Second, you can not change his name or have him adopted without his fathers consent. You can file a petition for his name to be changed but if the father contests it usually dosen't go through. If you have been remarried for at least a year and want your new husband to adopt you can also get a lawyer to file that but again it dosen't automatically happen especially if the bio father contests.