We are left with two mysteries (beyond the virus), the helicopter in Atlanta and what the doctor told him.
If they follow the comics, the second one is really easy to figure out. Granted the show is about 85% different from the events in the comics (no CDC or hillbillies with crossbows in the comics), but having read the comics, it seemed pretty obvious what the doctor told Rick.
I'll write it real small so it's tough to read. If you want to see it, just copy and paste in Word or something - Lori's pregnant.
We still havent seen how he gets to the place he was in the first ep when he shoots the kid zombie though right?
So that still has to happen??
That happened between Rick raiding the police station and leaving Morgan and his kid and Rick finding the farmhouse with the horse. He was in the police car at that time and running out of gas. No need for any further explanation, it was just a scene to grab the viewers.