Here's information on
worker's compensation in Georgia, and
links to resources.
You have two cases because you had two separate injuries, or did you somehow get two open files out of a single injury?
I don't know what you are talking about, in relation to a statute of limitations. You filed your claim back in 1999 and are getting benefits, so the statute of limitations isn't an issue.
If you decline surgery that could improve your condition, that could lead to a smaller settlement offer. The nature and terms of any settlement offer are up to the insurer.