SlimRider

IMHO, right now your priorities should be in this order:

1) Secure a decent chromoly steel bike from the 80's era that's in fair-good condition (doesn't matter if it's a cyclocross, road, or hybrid bike).

2) Handlebar type shouldn't matter. If you have flatbars, that's good, because you're not cycling a great distance. If you have dropbars, that's fine too, because you can ride the hoods to maintain an upright riding position. You can always assume a more aerodynamic position whenever you get ready.

3) A rack would be fine, but it's most definitely not a deal breaker. Besides, you're only cycling for approximately 7 miles one way, at the most. That's only about 25 minutes of backpack time. That's not much time to work up too good of a sweat.

4) Fenders aren't that necessary, unless you plan on many days of wet riding. Since you have a car, it's not that difficult to figure what you'll do on those wet Georgia days.