I'll address both sets of questions with a single answer. No, Rocket Man is highly unlikely to give up his nuclear weapons research without a fight. Or, at all. However, there is an opening and we should take it. Are you two suggesting we just admit that he's unlikely to give up his nukes and walk away? Or, as I've asked before, you're not suggesting military action, are you? That option should always be on the table, but should be exercised only after options that put the pain onto the bad guys rather than on us.
As for not having mentioned other serious issues, that's not how it works. You get the guy to the table first and then lay down the law. There's other ways of doing it, and past presidents have tried some of those methods, with no success except to Kim.
And, what is the number one issue we need to resolve? Otto Warmbier? As much as it makes my blood boil what they did to him, and the fact that they have so far gotten away with it, we need to deal with the existential issue first. Then Warmbier.