Adam's answer is spot on, and I'd just like to augment it a little.
For questions: there's closing. Or rather, putting on hold. That's the method we have to send a signal that "this post isn't currently up to scratch, but it can be made good". However, I think that when closing, it's incredibly important that we have a comment left along those lines: that while this may currently not be OK for us, it can be, and the "hold" is temporary.
For answers, we don't have anything quite like closing. However, it is still important - as Adam says - that answers are given a chance to improve. Unless answers are really obviously bad (spam, irrelevant, should be a comment, etc), we should comment and leave a while for edits. If they don't happen, then deletion is the way to go.
And a request, from me to everyone - please please please flag stuff. On questions, if they're not up to scratch, flag for closure (not VLQ, because that sends it to the Low Quality queue, whereas a close flag sends it to the close queue, which is where it should be). On answers, if they're not up to scratch, comment, flag as VLQ, and we'll come along and take a look, comment, and mark it for review a few days later.
I've just gone through the list in your question, and taken what I think are appropriate actions on all of the posts you've listed. However - I can't pick up on every answer that comes in, so if you see any more please flag them.