What is ONE effect?
Given the space on the cards, it would probably be more accurate of the FAQ to say that each separate sentence is considered a separate effect (although multiple sentences can share the same costs, play restrictions, etc.).
The Raven attachments are a good example. Each sentence is considered a separate effect. So, for example, if the Black Raven is out and, for some reason, it cannot be summer (there's an agenda that does this), the second sentence (about taking additional gold) is still active and applicable, even though it is not summer.
Other examples include things like, "Search your deck for a character card. Shuffle your deck." or "Lower the cost of the next attachment you play this phase by 1. Ignore all gold penalties to play that attachment." In both cases, the first and second sentences are totally independent, so even if one cannot happen for one reason or another, the second can.
Given the space on the cards, it would probably be more accurate of the FAQ to say that each separate sentence is considered a separate effect (although multiple sentences can share the same costs, play restrictions, etc.).
The Raven attachments are a good example. Each sentence is considered a separate effect.
...

You might be over-doing it a bit and taking the word "effect" too literally.
Remember that a card's text/ability is split into:
1. Cost,
2. Play restrictions,
3. Targeting requirements, and
4. Effects
Just because each sentence on the card's text represents a separate effect that can resolve independently of each other effect does not mean that they are treated individually when something refers to an "effect." All effects that share the same initiation (#'s 1, 2 and 3) are part of the same overall "effect." So a card like Rickon that says to copy "an effect that allows you to search your deck" does not pick and choose the part of the overall card text that does the actual searching. Anything that shares the same initiation would be copied by Rickon. And all restrictions on that search are going to be copied along with it - as if the copied text were initiated a second time - because otherwise, all you'd copy would be "search your deck" without ever having the information (from the play restrictions) for what you are searching for.
So, all the cards you mention, if copied by Rickon, essentially trigger the original card text a second time (just without paying the costs; those are replaced by "paying the cost" for Rickon).
As for the bit about "choose an opponent" being a separate effect, it is and it isn't. Technically, it is an independent part of the overall card text that simply chooses a target (and not doing anything to that target) as its only resolution. But none of the rest of the card's text means anything (and would therefore fail) if you do not identify the target player by resolving that choice. Essentially, there is no practical difference between, "Choose a character. Kneel that character," and "Choose and kneel a character." It's simply a style point - one that tends to become more necessary the more complex a card's text is.