How far along is your auto, and what medium (soil, coco, etc.)? If your in soil don't give them any nutes until at least the 4th set of true leaves. Auto's are pretty picky when it comes to nutes but still pretty hardy plants. If your growing in a soil less medium then I'd start at 1/4 strength until about the 4-5th set of leaves. Then you can move up to half, after that slowly up the nutes until she burns a bit on the tips than dial it back down and your good to go.
As for watering them, if your planting right into the final pot like I did then I'd probably use a 16oz bottle (make sure you do your fractions right 1/8 gallon) then as they get bigger you can use more water. Mine I water a few of the bigger ones with about 1/2 gallon of water.