Females will have a saddle. It looks like an orange saddle right behind their head on their upper back.
Be careful with fluctuating ph, it can kill the shrimp.
GH and KH are pretty important also, I learned the hard way.
I ended up putting coral bones in my filter to solve that issue, it raises the ph, kh, and gh.
Anyway, heres how I learned=
Oh yeah, most algae wafers are pretty high in protein and if your gh/kh is low(low amounts of minerals in the water) you can actually kill your shrimp by overfeeding because they wont have enough minerals to generate a new shell before they bust out of their old one. In your pictures you can see the shrimp having a line in the center of their body, that seemed to be what was happening before mine had started dying. With moss in the tank they wont starve, I usually feed mine algae wafers twice a week and they get some flakes that the fish miss.
Not trying to be scary or anything, rcs are pretty easy to keep, shrimp in general are still less hardy than fish in my experience though.