Yes, there should ideally be a 1 to 1 ratio of trope to work examples except in cases of "Subjective Tropes", which specifically direct you not to place the example on the work page.
For any tropes that don't have that warning, feel free.
Visit my contributor page to assist with the "I Like The Cheeses" project!Generally, yes, to all your questions. The main exceptions are if the trope is an Omnipresent Trope, such that listing it on the trope article would be redundant (example: The Hero); or if the trope is tagged as Subjective or Flame Bait, in which case examples should not go on the work page, but rather on its YMMV subpage.
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"Just as There Is No Such Thing As Notability for works, there is also no such thing as an unnotable use of a trope in a work. If a trope was used (and is not being shoehorned in), it is a valid entry.
If an article begins growing too large as a result of its massive trope collection and threatens to break the parser, then it can be corrected in a number of ways:
- Clean up natter and move subjectives to their appropriate subpages (a process which should happen anyway but is sometimes neglected).
- Split off a character sheet and remove character-specific tropes from the main page.
- Split trope examples by episode (in the case of a series).
- Create sub-articles for tropes sorted alphabetically (in the case of the truly intractably large articles where the above have already been tried).
For tropes, you can:
- Clean up natter, as above, including removal of Real Life sections.
- If it is truly an Omnipresent Trope, perform an Example Sectionectomy.
- Split the article by medium (Film, Literature, etc.).
- If it's still too large after medium split, consider making it into a defined subpage (like we did with Awesome Moments).

I found an example of a fourth wall break in the Wii game Little King's story that is not currently listed. If I want to add it, should I add it to both the "Little King's Story" page and the "Fourth Wall Break" page?
Also, if I see an example of a trope on a trope page that is not listed on the work page, should it be added to the work page? (or the other way around?)