Fire Shrimp Molting

I thought one of my Fire shrimps was ready to molt last night, it had turned slightly darker than the other, sure enough this morning the discarded shell was scattered across the tank bottom.
I have a couple of questions.
1. is molting every 2/3 weeks correct (3 molts in 8 weeks)
2. is it okay to leave the remains in the tank? I have for the first molts ;D
3. was the colour change to do with molting time, or is it because I have two fire shrimps and the darker one is male/female
4. the darker one is also bigger than the other, does that mean he will be the male?

oppps that was 4 questions :

just another note :- I find it great that the shrimp which didn't molt is staying close to the other seemingly protecting it.

 

Or the other shrimp may just be looking for a free meal should the molt go badly.

 

1. My cleaner shrimp molts once or twice a month.
2. I just leave in the tank, its gone in a day or two.
3. & 4. Sorry IDK

 

another question regarding Corailline response

1. is molting every 2/3 weeks correct (3 molts in 8 weeks)

Molting is influenced by many varibles, water chemistry, growth and stress, it's not uncommon for new shrimp to molt more frequently

If my water is spot on, and shrimps only get the food that my fish leave (not much) are you saying that shrimps could molt more because they are stressed? they are approx 50mm in size which I thought was not far off full size.

 

My fire and cleaner molt every week or two is seams like, peppermints don't as often but they are smaller and maybe I just don't notice. My fire is the dominant one of the bunch and usually gets first dibs when feeding