I think your point is well and reasonably stated.
I don’t really understand why people have the confidence they do about what Trump will do.
There is no meaningful record.
i do think what he has said in the past 6 months has largely fit what you are saying but I know that is not good enough for me.
Trump has been saying the exact same things on the trade issue since the 1980s in several interviews and in the full page ad he took out in the NYT and WaPo in 1988. He even gave a speech around that time in New Hampshire that dealt foremost with how other countries are ripping us off at trade.
As far as the other two main issues of his campaign are concerned, he first called for cracking down on illegal immigration and terrorists in his 2000 book, The America We Deserve. Terrorism in particular was a major focus of the book. He devoted a sizeable chapter to it and brought it up in various other places in the book. He also criticized Bill Clinton on the topic in the book.
In his discussion of the harm of illegal immigration, he specifically said that the interests of Americans needed to be placed before that of immigrants and that illegals need to leave the country. By the time of his 2011 book, Time to Get Tough, he was calling for a border wall. On the issues he's primarily running on, he's been pretty consistent over the years actually.