1)

(a) Rav Chaim Shmuelevitz zt'l (Sichos Musar, 5732, #32, page 119) writes that she is certainly not punished because of her husband. She is punished because of her own sins. However, if the husband would have fulfilled his own obligations properly, she would have been spared in his merit.

(b) Rav Chaim explains why it is specifically the lack of fulfilment of his financial vows which is the reason why she is not saved. He points out that the Gemara says that he does not have money with which to pay up. If he is not capable of paying, how can he be blamed? The answer is that if the husband would really appreciate the "Hakaras ha'Tov" that he owes his wife for all that she does for him, he would have made every effort in the world to obtain money with which to pay. Since he does not fully appreciate his wife, this is why she is taken fron him. However, it must be stressed that she dies because of her own Aveiros, not her husband's, but if the husband would have had a proper feeling of gratitude towards his wife, she would have been allowed to remain in this world in order to help him, Midah k'Neged Midah.

2) See Tosfos Yom Tov to Nazir 2:2, DH ha'Zeh, in the name of the Ibn Ezra, who gives us the following rule: "Anything which is not alive, Zachrehu v'Nakvehu" -- i.e., one can either use it in the masculine form, or in the feminine. Therefore, since a person's foot is alive, we say "Regel Achas." On the other hand, the Regel being referred to in our Gemara is a festival, which is not a live object, and consequently it is possible to use the masculine form.

Kol Tuv,

Dovid Bloom