They don't eat each other until L3-4, and they don't even start taking fruit flies until 2-3 days after hatching from the ooth.
Religiosa needs a diapause, or cold period, before hatching. Diapause usually is 2 weeks, fridge or outside works fine. Not sure about the hatching rate or incubation period though.
Incubation length can greatly vary depending on how long a cold period you provided for the ooth and the temperature at which you keep the ooth during incubation. Sometimes it can go up to four months before seeing any hatching. IMHO, I would give it a much longer cold period than 2 weeks. Something more like 2-3 months. Although a couple of weeks will suffice, mimicking nature is the best way to maximize your results. In temperate areas, true winter conditions last a minimum of three months...