NathanZee
Songster
Here I am to jump in! Actually some crosses of ducks can produce sex-linked ducklings. I did it by accident crossing my Buff Orpington drake and Mallard hen, resulting in tan-yellow females and blue males. I think there may even be a breed of auto-sexing ducks.Yes, you should clip one wing on each duck. This is for their own safety. I had mine fly to the neighbor's yard and not be able to get back over the fence. One ended up three houses down and I wouldn't have got her back except they knew I had ducks and called me. There are good videos on Youtube that show how to clip duck wings.
As for male vs. female, you have only two options. First is to learn to sex them when they are first hatched. This is difficult and takes practice but if you can learn it you will save money and probably be able to hire yourself out! The other option is to wait until their voices start changing at 3-4 months.
Unlike chickens, I don't think there is such thing as a sex-link duck that can be sexed at hatch by color. If there is, someone will brobaby jump in and tell us about it.
2 day old male.
The one on the left, slightly darker than the other two is a sex-linked female.
Juvenile sex-linked male.
Juvenile sex-linked female.