I've stored Agar pearls a week in advance, covered and refrigerated, no problem. I can imagine the ones that get dropped in a calcium bath would be more of a hassle, and have a shorter shelf life. The ratio i use is about 3 grams agar per 1 cup of liquid. I've had better results adding a bit more agar to more acidic liquids. If you're making a lot, I would also recommend filling 2 (or 3) tall containers with oil and refrigerating for no less than an hour. The colder the better. I swap between the 2 containers, keeping one in the freezer, and working with the other one. This way the liquid doesn't have a chance to heat the oil to a point where it won't cool the liquid on the way down.