Hello, I am also relatively new.
My understanding of the rare talents differs from what you wrote, so maybe someone with a bit more insight might be able to correct either one of us.
Now, by my understanding it works as follows.
About 5% of characters have these rare talent (at least that is the number I see getting used most places). These characters are usually part of the story but if I understand correctly they don't need to be part of the story.
Additionally to the 5% chance of even having a talent the talents have prerequisites. So if you were going the blacksmith route and got a combat talent, you might never find out that you even had one to begin with since you would need a certain level of combat skill to activate it.
As I said, this is just how I understood it, someone please correct me if that is wrong.