Nothing strange here. Imagine you're a male duck (a drake) who had a duck girlfriend who hated bread, but you have a new one who likes it. So the new kaczka je chleb, and you're a happy couple.
No, it's quite strange. Maybe you could say that in some context, for example if you had 20 ducks, bought a new one and wanted to emphasize that THIS new duck is eating bread.
Really? Where would you happen to say this sentence? Btw, im native Polish speaker.
You're at the lake feeding the ducks. But none of them want it. They know better. They've seen you before. You're bread is stale and hard as a rock. But the new duck... she doesn't know. Look! The new duck is eating bread!
I would rather used: This duck is eating the bread. Or that duck... but not the new...
And you're right. And also for 'not masculine-personal plural'. But here it has to be "nowa", feminine.
You look at the end of the noun and whatever letter 8s there is the one thats at the end 9f the correct answer