I am hoping Hawaii is too small a target to try for and definitely advise our foes to aim for the mainland.
I’m sanguine about it, not because I trust Kim’s decision-making ability, but because North Korea doesn’t have nuclear weapons. They do probably have a very small number of nuclear bombs, but a bomb is not the same thing as a weapon. In order to use those bombs as weapons, they’d have to get them to an enemy somehow, and there’s no evidence that they have the capability to do so. I much prefer for Kim to fixate on nukes that he can’t effectively use, than on the masses of conventional artillery aimed at Seoul which he can.
I live in Miami. One of the places I suggested they hit instead. Yes, we’re all kidding. And I hope we know it. 
Nope, at the contrary. When you have few nukes and your ennemy has many, detterence can only work if you target primarily population centers. Otherwise, you’re left with no weapons and having done little damage to the ennemy (and the ennemy perfectly able to retaliate in a massive way, as you pointed out), that’s no deterence at all.
The potential ennemy must know that messing up with you is the equivalent of suicide. If you have only 100 nukes, your stance should be that you’re going to launch them at the 30, 50 or 100 largest cities, leaving it totally crippled and devastated, regardless of what it decides to do next.
Targeting launch sites and such was only a policy of the USA and the defunct Soviet Union, who had an huge nuclear arsenal, and could afford to waste part of it in an attempt to “prevail” in the nuclear exchange.