Since Perception checks in DS use Intelligence, aren't they basically already Knowledge checks here (or at least common sense checks)?
Still, there is the Perception talent. Disposing of it could be an interesting option to make other talents more interesting (and giving scouts more much needed talent slots...). Noticing an approaching sneaking opponent could be rolled with Stealth as a bonus, finding traps or secret doors could benefit from Craft talents, with spotting something far away even Marksman or Sharpshooter might help.
Yes, I think that is something to consider...
Perception checks are usually silly. As a GM you usually WANT the players to find the hidden thing, anyway.
Yes, it takes a bit of skill and discipline to keep a session going with crucial perception checks failed. I think a GM should consider the pivotal points of his adventure,
not rely on the players to notice certain things and have the question answered for himself: "What happens, if the players do
not find this important clue?"
Another option I try to use as far as I can is letting perception checks not only be a matter of Yes or No, but also about quality, and I also try to consider
how well a perception check succeeded. This can range from "There is something off, to the left from you" to exact details like "You notice a narrow fissure in the wall, which obviously hides a blade. Below, you see a row of tiles which are slightly different from the other floor tiles and are probably trigger plates."
Depending on that, the findings may require further investigation, which results in clues depending on
how exactly the players conduct their further search.