Ok. Sexing juvie shrimp is nearly impossible. Once they reach sexual maturity, females will show a 'saddle', a light colour spot behind the head. The saddles is in fact her ovaries with immature eggs, and signals she is able to breed. She will moult and then send out mating pheromones.
Females are bit larger, and have a rounder underline than males, and tail fans can have slightly different shapes, but it takes some practice to see the small differences. I just wait for the saddles to show up.. if there is no saddle, it's a male. Females often also have stronger colour than males.
You can feed them tiny, tiny pieces of greens, like spinach. Boiled well, to soften it. They also like meaty foods, and will happily eat each other if one dies. But tiny amounts are the key, and if you use a feeding dish it helps keep it all in one place.
They eat almost all the time, but in such small amounts, most of us feed only a few times a week at most. They are scavengers, and very good at finding things to eat. Much of what they consume is just biofilm. Some of the specific shrimp foods, like Repashy, are good, as are other shrimp specific foods, which have colour enhancing antioxidants in them and calcium to help maintain good shells.
Females carry eggs approx. 4 weeks, and can moult and be berried again not too long after they drop the babies, but I'm not certain just how long after birth it can happen. From birth to full size is around six months, but I believe sexual maturity can happen at around four months. This may vary with species, variants or the conditions they are kept in.
