Oh, congratulations! And adult ducks need somewhat less intensive care, and a less steep learning curve, I feel.
So, check out the Stickies at the top of the forum, and keep coming back to read and to post.
Meanwhile,
Ducks, being waterfowl, need to be able to wash off frequently, so a kiddie pool is good to have. They can be fed poultry layer with crushed oyster shell on the side.
Their legs are easily injured, so don't grab or hold them by the legs.
Each flock is a little different, by the way, yours may need a slightly warmer shelter, or not.
Fresh greens are very good for them. This could be lettuce, but it could be chickweed and dandelions. They are good foragers.
I recall the BEIs are seasonal layers. And I think you may need to clip wings. I hope someone who knows for sure will check in here.
They do not roost, they are ground-nesters. And very susceptible to predators, so a little Fort Knox shelter is needed.
I hope this is a good start.