“Ignorance has nothing to do with it. Are you arguing that foreign entities will ignore disrespect they are shown just because there is no governance (yet) to back it up?”
No, they’ll make a public statement and seek reassurance from the other government representatives who aren’t notoriously reckless and idiotic. Public posturing is not substantive harm.
“I don’t think the Republicans would suddenly forget why they want a Republican president if Trump beats Clinton.”
That is precisely the point—the entire GOP fought Trump at every turn prior to clinching the nomination and large swaths of it continue to fight him because he isn’t actually a Republican.
As for locking him down, (A) the Democrats can do that by themselves because the GOP won’t have a super-majority in the Senate, the approval of which is necessary for the President to populate his/her cabinet, nominate Supreme Court justices, etc.; (B) why wouldn’t the GOP do this? The 2016 election features two candidates with incredibly low favorability and trustworthiness numbers. The winner will have exceptionally low popular vote totals and can easily be cast as a repudiation of the alternative instead of riding the mandate of the electorate.