Doesn’t matter. Cruz would never be an acceptable nominee. He didn’t win the voters and they will reject him again.
Yes, and no. Cruz was first runner up in this beauty contest, while Trump definitely owned it. If Trump is genuinely unable to finish (because of something real and not just his delegates turning traitor on the first ballot), voters would be okay with Cruz stepping in. Ted Cruz had little chance against Trump, but he decisively beat everyone else.
Cruz v. Hillary is not a sure thing either way, and that's as much as you can ask in such a situation. Fortunately, that is an unlikely hypothetical. Still, I'm glad Cruz is preparing for it, just in case.