1)
Why did they say "Yulad Ben l'Na'ami"?
1.
Torah Temimah citing Sanhedrin 19b: Because she raised him, he is called on her name. This teaches that anyone who raises an orphan in his house, the verse attributes as if he gave birth to him.
2.
Malbim: Via Yibum, it was truly her son.
2)
What is the significance of the name "Oved"?
1.
Malbim: In the future, he will serve Hashem. He is Yishai's father, from whom sprouts Malchus Beis David.
