For the first couple of weeks, depending on species, you can keep them together. Then seperate them. But, if they are a valuable species and you want to save everyone possible I would put them each into their own containers. I use 1 gallon rubbermaid jars.
Butterfly mesh cages work well. You can get them at Livemonarch.com. For 100 + nymphs, I would use the size that is about 1'x1'x2'. Feeding is then easy, just shake a bunch of fruit flies in every couple days. Mist once a day to help molting.
With enough space and enough food, they can be kept together for several molts with minimal losses.