1) The Gemara later (50a) cites the verse, "Happy is the person who observes justice, who does Tzedakah all the time." The Gemara asks, how is it possible to do Tzedakah all the time? It answers that this is referring to someone who feeds his small sons and daughters.

2) This implies that the Mitzvah involved with this act is the Mitzvah of Tzedakah, and this is confirmed by the Rambam in Hilchos Matnos Aniyim (10:16) who writes, "Someone who feeds his 'big' sons and daughters, whom he is not obligated to feed, in order to teach the sons Torah and to guide the daughters in the upright way... this is included in the Mitzvah of Tzedakah and it is a great form of Tzedakah because one's close relatives take priority in the Mitzvah of giving Tzedakah." The Kesef Mishneh writes that when the Rambam says "big" children, he means over the age of 6.

3) Since the Rambam there is discussing the Mitzvah (Devarim 15:8) of "You shall surely open you hand" to give to the poor, we may say that this is the Mitzvah which the father does when he feeds his children.

4) Yes, the Maharsha in Ta'anis (23b, DH Sachir), commenting on the account of Aba Chilkiyah, writes that this was the reason why Aba Chilkiyah did not answer the Sheluchei Beis Din. He was poor and had to work in order to do the Mitzvah of feeding his small children, as the Gemara in Kesuvos (50a) says that this is a Mitzvah.

5) A person who is busy providing Mezonos is not exempt from Piku'ach Nefesh, because the Gemara in Sanhedrin 73a tells us that one is obligated to lose money in order to save a life. The Mishnah in Bava Metzia 30b discussses when one does or does not break off work in order to return a lost item. The Rema in Shulchan Aruch (OC 108:8) writes that one should not miss the time of Tefilah in order to avoid a financial loss.

All of the above is certainly not intended to be a practical Psak, but is merely a brief summary of the Sugya.

Kol Tuv,

Dovid Bloom