Well done research. This was something I was thinking of looking into myself and you have ably laid out the facts. What I would like to add is some conclusions.
Is a largely symbolic policy gesture worth the high cost? How about investing that money in a better workplace verification system, as well as, public service announcements and economic aid to the countries that make up our undocumented population?
Another question to ask is how our acceptance of people — regardless of skill level — benefits developing and economically stagnant countries? Isn’t this counter productive when we skim off the best and the brightest? Isn’t that a form of intellectual imperialism? Isn’t that especially true when we are talking about high skill occupations? Doesn’t Honduras need more high skilled doctors then the United States?
Related to my last point is this question that never seems to get asked: Why do we have to import high skill labor at all? Why are we not developing and employing enough of our own doctors and software engineers? What education polices could be enacted to achieve such a result?
Finally, we need to accept an honest truth here. Nobody who wants immigration limits can then complain about the costs of goods and services. There has to be a acceptance that things will cost more if US labor is deployed almost exclusively at all levels of our economy. If voters are unwilling to accept these simple truths, no wall will ever be high enough or long enough.