The first two examples use a modal Relativadverb wie that refers to the meaning of the whole clause that they're embedded in. If you're coming from English, you could remember the construction like this:
*The suspect is a man, how police says.
(Dudenband 4, Randnummer 1744)
The third example with "wo" is a local Relativadverb which has an implied reference. You can add the reference by yourself:
[Dort] ist es kühl. (lit.: There is it cold.)
[Dort, wo Bäume wachsen,] ist es kühl. (lit.: There, where trees grow, is it cold)
[Wo Bäume wachsen,] ist es kühl.
Implied references are possible with at least some of the relative adverbials (or all?). I marked the implied references with round brackets.
Sie öffnet die Tür [(so), wie sie es immer tut].
Sie glaubt [(daran), woran er glaubt].
Sie verlangt [(das/etwas), worauf sie keinen Anspruch hat].
I also noticed that putting the adverbial in first position does not always sound good with these, but should be grammatically correct?
Maybe someone else will add this information to their answer, but I hope it gives you the right direction.
(Dudenband 4, Randnummer 857)
Mr Dursley konnte Leute nicht ausstehen, die sich komisch anzogen – wie sich die jungen Leute herausputzten!
From the -, you can tell that this clause was pushed in. The bold clause can stand on its own:
Exclamative sentences have forms of other sentences, but with an exclamation mark (and different intonation).
One way to form an exclamative sentence is through
[W-word] [rest of sentence] [verb]
This same construction shows up in repeated questions:
A: Welche Farbe hat das Auto?
A: Welche Farbe das Auto hat. <- This is a question
In which case the question is a secondary clause that can stand without the clause it is embedded in:
A: (Ich habe dich gefragt,) welche Farbe das Auto hat.
One thing is clear: Wie in your sentence is not relative.
What exactly the grammar is behind these exclamative sentences - I don't know. There is this book written about it, but unfortunately, it is $100.