Mid-season finales have been around for AGES and practically every single solitary drama has a mid-season finale. The reason actually makes a lot of sense.... tv networks found that the ratings for shows dramatically decrease between thanksgiving and new years. People are busy with the holidays and/or watching christmas specials and don't watch their regular shows.
They usually stop airing a show around thanksgiving (even if they don't officially call it a mid-season finale) and pick it up again mid-Jan. Unfortunately AMC, BBC and some of the odd-ball networks sure do stretch this out with their second half of the season not starting until spring.
About the points:
Zombies indeed only eat living things, this is why they fed them live chickens instead of killing them first. This is actually true in the animal kingdom.... some species refuse to eat anything dead unless you practically cram it down their throat.
People die for various reasons besides zombies. Starvation, suicide, carbon-monoxide posioning (the likely cause of the dead in the sub-burb given the fire downstairs), other people, heat stroke, old age ect....
Typically a zombie is indeed made when a person is bitten and gets away. This is a very efficient delivery method, at least initially. Think about it, one zombie or a few zombies aren't a threat.... you are suprised, get bit and easily run away and/or kill your attackers. You then re-join your little group and you appear "sick." Everyone falls asleep for the night, you die and turn and then go around eating everyone in your sleep. You probably aren't going to last, but you've probably managed to bite at least two or three people before you off you... and the cycle continues until in a society that lacks any communication, your group determines for themselves that a bite turns a person.
It could go either way with the farm. On the one hand it is psuedo isolated (not THAT isolated as it's just off the interstate going out of Atlanta) and there is a large buffer of land between the house and civilization. On the other hand, the interstate is just a mile away and if you've ever been on a farm, they stretch the definition of a fence to it's limits.... they are generally nothing more than some logs stuck into the ground with a bit of wire linking them. Sure it'll hold in your livestock because horses/cows/ect are weary of crossing fences, but it wouldn't hold out people.
In general though, walkers just wouldn't have any reason to wander so far off the beaten path to the farm. There isn't anything keeping them out, they just don't have any reason to go there.
This is something that has always bothered me about zombie films/ect.... They act like you have to go to alaska or an island or something to escape the zombies. That's just silly. In the North America at least there are TONS of out-of-the way places with a decent climate, little to no people, and virgin woods.
The problem though is globilization has made the entire world incapable of living off the grid. If the zombie apocalypse hits, you don't need to worry about weapons, you need to learn about farming and have tons of usable seed and people talented enough to get the stuff growing without fertilizer and pesticides and genetically manipulated starter plants. Oh and how to survive without a power plant and water treatment plant.