My duck grew up with 3 chickens...they are all best friends and sleep and snuggle together.
Chickens naturally have a pecking order and now and again the duck gets a little peck as do the smaller of the 3 chickens...but nothing nasty.
I know from experience that just chucking new chickens/ducks in with a lot of other chickens without introducing them properly can result is some extremely horrific confrontations...I didn't do this, but someone who lived close by who didn't care did this and I had to watch the events unfold over a number of weeks. I lost count of the times I had to go on their property and rescue a poor critter that would have otherwise been killed. Their attitude was "well, if they die then they die...we'll have less then"...Well why did you buy more?!!! Grrrrr!!! They ended up leaving them outside for a fox to eat and then the RSPCA were called in.
As for dogs...that completely depends on how trained your dog is and it's temprament.
I used to have a dobberman who wouldn't harm a sausage. She just used to lick my sisters guinnea pigs and my very small lizards and used to catch wild rabbits...but then just lick the rabbits as she thought they were guinnea pigs...silly dog.
If the dog is well trained, and it knows you're alpha male then you shouldn't have an issue.
Just remember, an untrained dog is a potentially dangerous dog.
Just make sure you introduce them slowly.
Woka