Yes a cinnamon could be either sex. Caution should be shown with pieds since they can have a condition called "tricolor" where some sections of feathering look cinnamon when cinnamon genes are not present. Better pics of the chick may help.
I don't know, it looks awfully cinnamon to me. But mom is also a cinnamon which means if the baby is cinnamon it could be either gender.
If dad is split cinnamon and mom is a visual, baby can be either gender. If mom was not cinnamon and dad is split, baby is female. Because mom is a visual cinnamon pearl, baby is either. And because baby is pied, it's going to be really hard to tell gender without a DNA test.
If you have experience with cinnamon I will take your word for it. This mutation can sometimes be tricky to identify over the internet for a number of reasons. Firstly because there are other diluting mutations like Emerald, Fallow, Recessive Silver, Dominant Silver, and Pewter. Secondly because lighting conditions and monitor settings can affect how each bird appears to each person. Seeing the suspect cinnamon bird in person is always better.