I use 1 quart of water, 2 tablespoons of API Aquarium salt, and a half tea spoon of brine eggs.
I doesn't matter what salt you use, just don't use tablesalt, also if you have pure water it is better, you don't want to use tap water.
I don't use airstones, I just hook some airline to a piece of ridged airline and stick it in. adjust your air so it is just enough to keep the eggs off the bottom.
After 24-36 hours, shut the air off for a few minutes, and let the brine settle to the bottom, then just siphen them out into a new jar. The hatched eggshels will float to the top, and any eggs not hatched will sink to the bottom. It also helps if you turn off the room lights, and put a flashlight near the bottom. The baby brine will be attracted to the light, and it makes it a little easier to get them all out.
My eggs almost always hatch by the 24 hour mark, but the time it takes will depend on the temp of the water.
Also if you are using eggs that you just picked up from a petshop, don't be surprised if a lot of them don't hatch. Brine shirmp eggs should be kept cold at all time till they are ready to be put in water to hatch, so eggs that have been sitting on a store shelf usally have a lower hatch rate. I always order my eggs online, and when I get them keep them in the refrigerator. I normaly get them from brineshirpdirect.com, and always order the premium eggs. They have a much higher hatch rate.