(I'm not good with quotes so you'll have to forgive the lack of clear direction on what responding to).

South Korea has been more conciliatory, but impression I got from quotes from the PM was that part of their negotiations was helping to get Trump to meet Kim, so if he didn't, that may have started falling away as well. Plus, I think for better or worse, some of Trump's actions prior helped push S Korea to being more conciliatory.

While part of the timing might be due to domestic issues, based on past efforts, I do feel that without Trump fronting early on, negotiations would have gone nowhere.

Regarding media - I tend to use CNN and BBC (plus local NZ news outlets), but I found CNN seemed quite consistent in criticising each step of the process, regardless of the twists and turns it took. The one exception to this was one piece saying that Trump's efforts did actually seem to be working, but that was quickly drowned out by other articles outlining different issues - Trump is being too accommodating for a rogue state agreeing to the summit stuff too early, then suggesting it was a disaster when he then stopped being accommodating and threatened to cancel the summit, but then back to being too accommodating when it went back on. Maybe I'm reading too much into their pieces, especially the opinion pieces, but CNN does seem quite ready to print opinion pieces criticising Trump, and while it may be different opinionists each time, CNN is happy to print them all, leading to the feel that whatever Trump does, CNN is going to find an opinionist who will criticise it, making it clear where they stand.
Thus while I find CNN better than Fox, and good source of other world news, when it comes to Trump I can trust that they will criticise everything he does, and it lessens their credibility, not his.

BBC on the other hand doesn't seem as bad, perhaps doesn't give their opinion pieces quote so much prominence.