To my ear, the PEU examples are both colloquially natural and accurately described, while the Macmillan examples, although colloquial, are somewhat misleadingly described: things that are happening now might be better expressed as things that have just happened or have just been reported. But that's a minor criticism.
All these examples exhibit the same basic use of will to express habitual or characteristic action. In this sense (like all the modals in all their senses) this habitual will employs its tensed forms, and particularly the past-tense form, to express nuances which may have little or nothing to do with tense. Speaking very broadly,
Ordinary unstressed uses usually express simple habit—behavior repeated frequently over a long period of time—and tense has its usual significance of present or past reference:
When he's preoccupied with a problem he will often pace up and down for hours.
When I was a child we would always go to my grandmother's for Thanksgiving dinner.
When will or would is stressed, the sense is somewhat different: the habitual action is represented as perversely deliberate. And the tenses are employed somwhat differently, too. The present-tense form generally signifies that the subject currently makes a habit of the perverse behavior:
She will keep falling in love with the wrong people is rhetorically equivalent to She insists on falling in love with the wrong people.
But the past-tense form, although refers to a past action, does not express repeated action in the past but represents the subject's behavior on a single occasion as characteristically perverse:
You would tell Mary about the party ... Even though I asked you not to tell anybody without checking with me, you just can't control yourself around her.
A: He said it was all Jack's fault.
B: Well, he would say that, wouldn't he. Nothing is ever his fault, oh no!
Tom is the best expert ...
Assertion of a fact. Where there are agreed criteria then there's no need to hedge an statement.
Djokavic is the current number one male tennis player in the world
When criteria are less certain, or we ourselves are not sure of our facts, or we wish to be modest by appearing to be uncertain of our facts we may use I think
I think Djokavic is the best male tennis played of all time
I think that the population of the UK is 50 million (actually 65 million)
This formulation implies that we are open to correction and discussion
Adding would softens this further, emphasises that we are uncertain
I would think that the population of the UK is greater than 50 million
The I would have thought formulation is normally used in a context where some information has recently been given. Depending upon the context it may imply that we are actually contradicting the information, or that we are expressing surprised acceptance.
I think Tendulakar is the best batsman of all time
I would have thought Bradman had a better record
that was disagreeing, suggesting that by some criteria Bradman is better
The current UK population is 65 million
Oh, I would have thought it was only 50 million
but now I've changed my opinion (this implied but not said)
that was agreeing, I thought it was 50 million, but I accept your statement of 60 million is correct. We could just say
Oh, I thought it was only 50 million
With pretty much the same meaning, the slight difference being that the second case implies it was actively in my mind, whereas the would form could imply that I hadn't really formed a solid opinion until now, but I would probably have guessed 50 million.
As your comment indicates we are indeed into shades of meaning and idioms. In these cases the tone of voice will often differentiate the meaning.
I would have thought Bradman had a better record
Would probably said with a questioning or challenging tone and raised eyebrow.
Best Answer
You are partially correct in that stative verbs usually relate to a permanent or extended state, and you cannot use would to describe a permanent or extended state. For example, you cannot replace used to with would in these sentences:
We use would about regular, habitual actions- a number of separate occasions over a period of time: that's why you can't use it for permanent of extended states.
You are also correct in saying that know can be a stative verb. If you know something, then (assuming you don't forget) it's not a temporary thing.
You can, however, use know in a non-stative way, for example if you were to say
What this means is that, on every separate occasion that a question was asked, John did, on every separate occasion, know the answer.
This link provides more background information about would and used to.