1. We need to lay out three 'paths'. First, if you are a resident alien/migrant (with or without a Green Card)....with a ID problem (fake ID, or unwilling to show any past history)....you get isolated and put on a deportation list. If you have a criminal history in the old country, or the US....you go to the deportation list.
Second path, you show you are unregistered and undocumented....but having worked, and no criminal behavior....we put you onto a Green Card-Lite program. You can work...pay taxes, and contribute to Social Security. After five years of displayed 'good-character' and no criminal stuff.....you go to the permanent Green Card. If you want to convert that to citizenship....show a ten-year period of good-character.
Third path, Develop a short-work (six-month) visa. No Social Security contribution, and the hiring authority has to pay you minimum wage. No federal/state taxes. At the end of six months.....you return to your country voluntary. You stay there six months, and then can reapply for another short-work visa.
2. Mandate a TB test, and IQ test when entering on a visa. Whatever the American standard is for IQ.....you have to test within 10 points of that.
3. States will have the right to limit migration.