If you're already composting, it seems to me you might as well just put some redworms in the compost pile rather than doing an outdoor worm bin. They may already be in your pile in fact. I don't really see any point in burying a bin. Maybe I'm missing something?
To me the advantage of having a bin is that you can keep it in the basement or the garage. I live in New England, so this means that I don't have to go out into the cold to take stuff to my outdoor compost pile in the winter. That might not be so much an issue for you in SC, but it is still more convenient to put kitchen waste in a worm bin in or near the house than traipsing out into the yard.
And compost does happen sooner with worms on the job. I think it is better compost, too, although I can't really support my belief with scientific information. (Maybe someone else on this forum can comment on that.)
Chicken manure is hot. You should not put much in at a time. I have chickens and sometimes put in a shovel full of sweepings, which includes the poop, the straw and shavings, and the random rusty nail and stuff from the barn floor. If you do that, you have to make sure that there is somewhere for the worms to retreat to, 'cause that stuff will heat up. After a few days it cools back down and it is fine for the worms.
And tearing up newspaper is not so bad. Cardboard tears up easily if you leave the box out in the rain so it gets nice and wet. And composting is a much better thing to do with junk mail than sending it to the landfill.
mbetts

I'm not seeing how you're going to get the finished compost out. Are you going to pull the bin out of the ground to get the compost? These things get pretty heavy when they are full. Are you going to scoop everything out and do the hunt and peck sorting? Awfully time consuming, and I don't think it would be incredibly easy with a hole in the ground.

Personally, I would make a flow through bin of some sort, and place it in a slightly sheltered area. If it's big enough, it will withstand the temperatures.

I vermicompost because I don't put any effort into my compost bin. So far, I mostly just have grass in it, and I don't want it to turn into a sloppy mess with food inside of it. I also put weeds that I don't want in my compost bin in my worm bin, bindweed and such.

I don't shred the newspaper. Newspaper goes to the recycle bin. Junk mail is shredded and then put in the worm bin. Cardboard is occasionally torn up for the bin. All napkins and facial tissues are placed in the bin. Receipts, notes, any and all other small paper is put in. You don't have to tear or shred things up small, they'll just disappear quicker. About once a month I take an old phone book and tear some of it into strips to toss into the bin.

I had my bin buried to keep it from the summer heat. It tended to float when it rained. I put rocks in the bottom drainage bin, but have since filled in the hole. I'm in VA 8a and will be moving my outdoor bin to the garage next week when we get under 40. It'll probably come back out if the temps warm back up.

I started mine w/ newspaper, cardboard, coir. The only thing I add now is food once in a while and paper towel, toilet paper rolls.

I want chickens but it won't happen where I'm living now. I'd put the coop clean up in the regular compost pile. If you have a regular bin it could go in the coop to protect it from out side weather. The coop doesn't need to be heated but should be draft free. The chickens would love a few worms for a snack now and then. They like bsf larvae too.

Here is a link that might be useful: BYC Forum

You can do it in the ground without a box. The worms will stay where the food is. Large scale vermicomposters will use a windrow system. I've read about a study that used bins made out of cinder block and used like a windrow. Basics are you pile your bedding on one end of a path and slowly add food to the end of the pile. You will slowly make a long path. Then you can harvest from the begining of the path without having to separate worms from castings. Then you can start a 2nd path next to the first, and the worms will naturally migrate to it for the food.

I've seen in a green house where the owner kept the worm bin in ground, under his walkway. He just dug down and put cinder blocks to hold the shape. Then filled the hole with bedding and food. Easy but requires a little more work to separate the worms.

Natives will come in also. You can put a tarp down to keep your worms in place, and natives out.

Can't give you a size idea. Start with something about the size of a 18 gallon rubbermaid tote.

Vermicompost is better than regular compost. I think I've read that it is like 10 times better, but can't find that information right now.

If you have chickens, you can fee the chickens with some of your worms. You can also slowly add some of their droppings to the bedding, but not too much at a time.

I'm going to give you a link to a really good pdf that someone suggested to me. It'll give you information from studies done with bedding and food types along with bins and other systems.

Here is a link that might be useful: Manual of On-Farm Vermicomposting and Vermiculture By Glenn Munroe Organic Agriculture Centre of Canada

In areas that reach below freezing I think buried bins are the only way to go. I have over three hundred sq. ft of bins that are buried. I would not consider any other way at this point. Heat in the winter and cool in the summer.

Two things to keep in mind.

Put it where it can't flood. And when the cold temps start have thick enough bedding/casting to insulate the bin and they can go deep to stay wrom if necessarry.