I think they were all honest. Unless Trump was lying and just playing games w/third party idea to have, as he said "leverage."
If he doesn't win the GOP primary and then runs as third party... that would be evidence that he wasn't lying, but it would be dishonorable.
I believe all the other candidates would support whoever wins the nomination and runs against the dems - as will I. I wouldn't count on Trump to do so; unless, again, he was lying in the first debate.
Depends on what you mean “support.” I am under no illusions that WHEN Trump wins, the RINOs will do everything they can to sabotage his campaign.