>There is no way of deporting millions of people without processing them through camps or detention centers of some sort.
Well, gonna have to research how Obama and Bush did it. If they can do it, Trump should be able to do the same thing.
>Which visa would a typical Mexican person apply for to immigrate to the US legally?
Well, how I came was, I had to apply for a Green Card to become a resident (legal immigrant) of the United States.
You can also apply for any work related visas that you qualify for (work visa is temporary residency only). Or, you can marry a U.S. citizen (permanent citizenship).
The good thing is, Trump plans to make the Immigration Process more efficient and faster for people who are legally migrating to the United States.