What are the underlying meanings of the listed ideas in A Modest Proposal?

In Swift's A Modest Proposal, there is an italicized section that is set apart from the rest of the piece; the italics ensure that Swift's words in this section are understood as serious, rather than ironic. A Modest Proposal is defined by its ironic tone and content, but this italicized section you refer to in your question contains Swift's genuine ideas about how to solve Ireland's problems at this time.

In this section, Swift suggests that 1) English landowners who do not live on their land in Ireland (called absentees) be taxed, 2) only goods manufactured in Ireland be on offer for the Irish to buy, 3) the Irish reject anything foreign that might tempt the Irish to break the aforementioned suggestion to only buy Irish, 4) the expensive habits of Irish women be discouraged, 5) being more economical in general is a good idea, 6) getting along with each other, 7) being more protective of Ireland and Irish pride in self, 8) encouraging landlords to be more compassionate towards their tenants, and 9) encouraging honesty and fair practices in shopkeepers.

Behind each of these ideas is a general sense of self-reliance, personal responsibility and a united cultural identity. Swift believes that Ireland can take care of itself, as long as the people of the country cooperate to preserve society. All nine of these suggestions encourage a strengthening of Irish culture that will simultaneously strengthen the economy of the country.

Ironically, Jonathan Swift was born in Dublin, Ireland, to English parents, and he attended school in Dublin and Trinity College, Dublin. But, later, he moved to the home of Sir William Temple, a retired diplomat, who resided in Surrey, England. Swift had hopes of becoming a clergyman; however, his satire on excesses in religion, A Tale of a Tub, ruined his chances. Then, he benefited from changing his political allegiances from the conservative Whigs to the Tory party favored by Queen Anne. But, when the queen died, Swift's hopes again were dashed as the Whigs regained power. Embittered, Swift returned to Ireland. Then, in 1729 he wrote A Modest Proposal which champions the Irish cause for freedom.

This embitterment is certainly evinced in his scathing indictment of the cruelty of British rule in Ireland that is cloaked in his ridiculous suggestions and monstrous humor, suggestions made because England was figuratively "eating"/consuming Ireland. For, at the time there was overpopulation, extreme poverty, and an unfair balance of trade and employment.

1. Swift suggests that children of the poor Irish be divided with 20,000 reserved for breeding, one-fourth of which are male. 100,000 should be sold to the rich at the age of one year because they can be nursed for one year.  The other babies can be divided into four dishes of "nutritive meat." Skins can be used for gloves and such.

2. As a solution to the superfluity of Papists [Catholics], British landlords can purchase the Irish babies for 10 shillings, which would bring a profit of 8 shillings since caring for children and purchasing the rags they wear would only cost 2 shillings. Then, too, the women would be more able to work.

3. The money for the babies will help the Irish economy. Taverns can offer the delicacies and increase their business.

4. Mothers will take better care of their children, knowing that they are profitable to the family.

5. Men will also care better for their wives; men will be more motivated to marry the women who carry their children.

6. There will be a reduction in thieves because there will be less poverty and fewer children to steal things.

What are the themes of "A Modest Proposal"?

The theme of this satirical essay by Jonathan Swift is apparently social welfare. The fictional writer of “A Modest Proposal” (a character invented by Swift) claims to have found a solution for the serious social problem of hunger. Because it is a satirical work, however, Swift’s real main themes are injustice and hypocrisy. Certainly, the Irish situation is dire, and people cannot afford to feed their families. There are many steps that need to be taken to remedy that situation. The ostensible writer fails to provide any real solutions but settles on a simplistic assessment of a highly complex problem. The equation he proposes is logical but immoral: there are too many babies and not enough food, so we should turn babies into food. By extension, Swift uses this reasoning to criticize other, equally draconian English policies toward Ireland.