Hard to say. Possibly but more likely they thought the indictment they presented met the legal requirements, and the judge simply disagreed.
Again, hard to say. It all would depend on what they chose to present to the jury. Having it dismissed before the trial potentially limits the evidence that the prosecutors can present (if, for example, the alleged conduct supporting those charges doesn't relate to the remaining charges), but the jury never hears about those charges and so if the other charges that remain are strong they could convict on those (and then sentencing would be based on the remaining charges). For sentencing purposes it wouldn't really matter unless the jury or court (whoever is doing the sentencing in GA state court) decides to impose sentences of consecutive jail time versus concurrent.
Again, hard to say on all of this. I don't know what the remaining charges are and what the potential sentences are for them. It might be a big nothingburger or it could be significant.