I think the odds for Biden are significantly higher than that. Best evidence is that Trump himself was in GA last week so both campaigns have internal polling that isn't inconsistent with public polling showing the race could go either way.
Also, in ATL, you have 2 competitive house races, 2 competitive senate races, in addition to the Presidential race. On top of that, the GA vote won't necessarily be correlated with the Rust Belt vote so it's a good diversification strategy should Biden actually lose of the Rust belt trio of states everyone thinks he's going to win.
No idea. A waste of money.
POTUS: 10%
Sen: 5%
SenS: 0%
So no idea. Go to Texas or Ohio or PA or lockdown Arizona instead