Hello,
about locations:
The world is not random generated. It is always the same, no matter how many times you start over the server.
The only "resource" on the map is Clay (that brown "scratches").
Ore is not really rare. you can be rather sure that every mountain/hill got some kind of ore hidden in it. You might have to dig a bit more then on the better spots.
Cant tell about gold and silver though, never found/searched it to be honest.
But Copper/Iron is available in big veins about everywhere.
You just have to prospect it properly.
How its done in a good way is hard to explain. Its like a triangular (doh... no im missing the english words ^^' i try to explain it).
you have like 6 fields like this:
_ _ _ _ _ _ (use the observe mode under terraforming)
you search the outer edges with a certain PROSPECTING range.
like:
6 _ _ _ _ 10 (changed the _ for the number)
which means,
6 _ _ _ _ 10
\ /
\ /
\ /
X
about the X will be your ore (underground) the 6 and 10 are the outer edges, where you can prospect the wanted ore. You need to perform a triangular "search" routine, damn! really dont get the word right now, to pinpoint how much you have to dig down and where to dig.
Normally you need a third point (since its 3D not 2D) to make it properly, but since its an ore vein, you will most likely hit it like this too. A bit of a guessing game
but once you get used to it, its not too hard.
Best regards, Ontrose