I'm thinking maybe cockerel based on crest shape. But won't know until around 5-6months of age. 3-4 months at the earliest. Every silkie matures at different rates.
That's a tricky one! I was going to say cockerel due to it's crest shape, but then again it's comb doesn't seem very obvious and it's stance is a low. So I'm gonna say try again when he/she is older.
Blacks and whites are the worst to sex IMO. This one looks female for now, but that could change. Keep an eye on the comb. If it gets big, it's a boy. If it stays flat, it's a girl.