What is the significance of the name "Orpah"?
Refer to 1:4:2:1.
Malbim: This shows like a Midrash says, that she did not convert. One who converted would change his name. This is why it says "va'Yis'u"; Torah marriage is Lekichah 1 . An expression of Nisu'in is used for Nochriyos in Sefer Ezra ("Nas'u Nashim Nochriyos" - 10:44) and Nechemyah, or when some wives were secondary ("Nashim Shemoneh Esre Nasa" - Divrei ha'Yamim II, 11:21; only two were primary).
It says Yis'u regarding Bnei Binyamin who married the dancing girls (Shoftim 21:23)! Perhaps because their fathers did not give them, it does not say Lekichah. (PF)
Here she is called Orpah. Elsewhere (Shmuel II, 21:16), she is called Harafah!
Torah Temimah citing Sotah 42b #1: Her real name is Harafah. She is called Orpah because all were Oref her 1 (had Bi'ah with her from the Oref (back)).
Torah Temimah citing Sotah 42b #2: Her real name is Orpah. She is called Harafah because all threshed [had Bi'ah with] her, like ha'Rifos (crushed wheat).
Rus Rabah 2:20: The night that she separated from Na'ami, 100 men and a dog had Bi'ah with her.
What is the significance of the name "Rus"?
Torah Temimah citing Brachos 7b: She merited that David descended from her, who RiVah (satiated) Hashem with songs and praises (Tehilim). Malbim - the Gemara asked why she did not change her name, like converts normally do.
Machlon was listed before Kilyon (2). Here it says that they married
Chasam Sofer (EH 1:130 DH v'Lich'orah): The Chida (in Simchah ha'Regel, citing a Midrash) says that Rus married Kilyon. He died, and she did Yibum with Machlon 1 .
Malbim: Verse 2 teaches that Machlon was the Bechor 2 . However, Kilyon married [Orpah] first.
Chasam Sofer: Normally, it is forbidden to marry a woman widowed twice, due to danger. Bo'az did not fear to marry Rus, for the Mitzvah of Ge'ulah would protect him. He did not rely on Mitzvas Yibum, for it was not absolute Yibum, and it did not protect Machlon. (How could he rely on Ge'ulah, which did not absolutely mandate marrying her? - PF)
Sometimes verses list children in order of Chachmah (Bava Basra 120a, Sanhedrin 69b). It is unreasonable to say so here, for both sinned, and the verses do not teach anything else that they did. (PF)
Why does it say "Shem ha'Achas
Malbim: (a) This shows the lack of Musar. The younger married first, b'Aveirah, and his older brother did not protest. (b) Had Machlon married first, we could have said that he recognized Rus' virtue - her end proves about her beginning - and Kilyon thought that he will find a wife like his brother. However, first Kilyon married the evil Orpah 1 . Machlon should have realized that his brother stumbled. Instead, also he sinned!
Where do we find that she was evil already? Initially she did Chesed with her husband and Na'ami (8), and wanted to return with Na'ami, just when she slackened, she descended terribly! And even if she was evil, perhaps Machlon recognized that Rus was virtuous - look at her end! (PF)
