Why will she act stealthily, and not overtly ask him to marry her?
Malbim: Na'ami and Rus were ashamed to request this overtly. Mekubalim explain that the body is the shoe of the Nefesh. A Neshamah cannot stand in this world without a body, just like a delicate, pampered person cannot stand in mud without shoes. This is why Hashem told Moshe to remove his shoes (Shemos 3:5, i.e. his physicality). One who dies without children, his Nefesh has no tranquility. It rattles in his wife. If a baby is born via Yibum, it is as if his Nefesh returned to the world; the baby is the dead brother, and is called on his name 1 and inherits him 2 - "Yulad Ben l'Na'ami" (4:17). Oved himself was like Machlon. The child is like the shoe of Nefesh ha'Mes. If the Yavam does not do Yibum, Nefesh ha'Mes is left without a shoe. Therefore, she removes his shoe and he is called "Beis Chalutz ha'Na'al" (Devarim 25:10). Rus hinted so to Bo'az via uncovering his feet and lying near him - either expose your feet to be called Beis Chalutz ha'Na'al, or I will lie by you to establish your relative's name in Yisrael, and your foot will be covered with a shoe.
Yevamos 24a: This is the only verse that leaves the simple meaning. There is no Mitzvah to call the baby on the Mes' name! (Even so, in a spiritual sense it is called on his name. - PF)
Yevamos 37b: One who does Yibum inherits his brother, even if a son was born. (Perhaps the baby inherits the Mes in a spiritual sense. I question Malbim's support from the verse - perhaps they said that he was born to Na'ami because she nursed him! - PF)
What will he tell her to do?
Malbim: He will command you to speak to the closer redeemer, or Bo'az himself will speak with him.
