New to ducks...Welsh Harlequins?!

[QuackandPing]

Hello all...we are new to ducks and recently purchased 2 Welsh Harlequin Ducks. They were unable to tell us the sex of the ducks at the time we bought them. They are now about 4 weeks old. Is there any way to know the sex by looking at the feathers coming in? They are drastically different. The one that is turning browinsh is Ping, and Quack is the yellow one getting the white and tan feathers. Ping has started quacking and does have a deeper more harsh quack. Quack has yet to, well...quack. : )
Also, we have them in a stall inside our barn. We do have a swimming pool for them to play around and drink from. How soon can they start going outdoors for periods of time, and how do we go about introducing them to it? Thank you in advance for any help! Here are some pictures...

Thanks for looking!

 

[Cetawin]

aaawwwww they are precious. It looks like a silver female and a golden male possibly female. When the head feathers begin coming in, you will know for sure....here are some pics of my golden welsh harlequins

You can see 2 drakes (boys) and one girl (duck) in this pic

This is my boy Draccus

This is my girl Nibblets

In this one you can see their backs in the pool