I don’t think a 1/2 acre is large enough for a commercial orchard. Essentially an orchard that small will operate at a loss. You may be able to sell some extra apples to defray your costs but again it’s not going to be profitable.
My suggestion would be to do the following. Buy 4-6 trees to get your feet wet and see if you really want to have a large orchard. There are people on the forum that have large orchards and people that have small orchards with few trees. You may actually be happier with a smaller orchard. Also you may find that growing apples as a hobby in the long term is not something you really want to do so there is no sense in buying a 100+ trees in the beginning.
Your in Georgia and have clay soil right? If that is the case this is what I would plant if I was in your shoes. I would pick two trees that have high resistance to the major apple diseases scab, fireblight, cedar apple rust, powdery mildew, and summer rots. It is almost impossible to get high resistance to all 5 diseases in one tree so spreading the disease resistance to the 5 diseases over two trees gives more options as far as cultivars you can pick. For example you could use Enterprise and William’s Pride.
Look at this list for disease resistance to scab, fireblight, powdery mildew and cedar apple rust:
For resistance to Summer rots which are usually not well documented look at this thread for two lists of apples resistant to Summer rots:
No apples really have resistance to insects unfortunately. So for insects you will have to spray insecticides, or spray Surround (a kaolin clay) or bag the fruit to protect the apples.
In 2 years after planting the trees you will have a much better understanding of the disease pressure in your local area. In 4 years you will have picked a few apples and better understand the reality of growing apples. After four years of experience you will be able to wisely pick any additional trees you want given your added experience under local conditions.
For the other 2-4 trees pick any trees you want but here are some suggestions. Avoid any trees that are highly susceptible to any apple disease. Susceptible is okay. Highly susceptible trees create a disease reservoir in your orchard and make it really hard to keep diseases under control in years where conditions favor their spread. This especially true with fireblight because it will kill trees and there aren’t really good control measures (sprays) you can use in a home orchard.
Popular commercial cultivars are worth looking at and so are popular widely planted heirlooms. Regional heirlooms that are popular in the South East could also work well. For example you might want to look at Arkansas Black as a possible choice.
Avoid rare apples for the most part. If all the descriptions use the exact same words and phases be suspicious…because probably no one is actually growing it. This also goes for apples that have short undetailed listings on Pomiferous or OrangePippin again few people are actually growing the apple.
For rootstocks in Georgia for clay soil I would look at G11, G214, G30, G969, G890, and M7 for dwarf and semi-dwarf trees. Do some research on cultivars and rootstocks and when you have narrowed your choices you can always post on the forum and ask for feedback.
Good luck hunting 