A) Mods are not on the same page because they are different people with different experience and definitions. Part of the reason I frequently ask about things (even if I'm pretty sure on other people's decisions) is because I want to know what others think and, more importantly why. I think everyone agrees, though, that consistency in this regard is needed.
B) I think everyone wants this. RandomMan has sort of stated the obvious though. We already have people who ignore the rules as is. While people who legitimately care about the site might go through and read all the rules, we also know that many user will ignore them not matter how short specific and clear they are. However, if you have exact suggestions on how to improve it, this would be appreciated.
C) The issue here is not "an image macro can be uploaded in more than one entry." I think just about everyone gets that there can be more than one copy of an image on the site. While I would not oppose a system that would change to this right now we can only go based on what is present.
The real issue is that an image should only be uploaded to equally relevant entries. As I explained here as well as noted in the KYM Image Gallery Guidelines "If an image can go into a more relevant gallery, do not upload it into one of the umbrella galleries (Such as Reaction Faces, Anime, GIF, Childhood Ruined, Childhood Enhanced, Alternate Universe, Tumblr and Crossover). It is okay to upload a single image or video to multiple galleries as long as the two are equally relevant."
A cross between two memes is equally relevant in either gallery for said memes. A cross between two subcultures is equally relevant in either subculture's respective gallery. They would not be equally relevant in an umbrella gallery that almost anything can fit into. Submemes for specific subcultures should go into their own respective galleries, not the main gallery for that subculture. Images such as these also encourage future uploaders to ignore full entries for things and just post to an umbrella gallery because it's trending and its what users in the past have done (follow the leader)
D) This is of course going to be subjective. When I asked about this image in IRC, decisions were split about keeping or removing. It really is not a Hentai Quote but Random21 has sorta a policy of "if the entire page is needed for context, then it's fine". The thing that finally broke the tie was noticing that the image was linking to offsite NC content, which is stated to be against site rules.
E) As much as the mods joke about ruining fun, we don't have it out to actively destroy it. This issue is that KYM is supposed to be a unique site, documenting internet and viral phenomena. It's not 4chan, it's not 9gag, it's not Reddit or any of the other sites that are dedicated to just posting random stuff people find funny. It is supposed to be more of a library or a database trying to catalog different things that have spread.
Which library/data base would you rather visit? One that is organized that people can easily just jump into things in addition to finding the exact thing they are looking for no matter where it is,
or one that people have to dig all over the place for to even know if the thing they are looking for is even present at all?
Don't get me wrong, there are certainly discussions to be had about how things should be organized. However, stuff like putting things into the most relevant galleries, while useful for people trying to find something, is seen as a "fun killer." The same goes for limiting user generated content about injokes.
Finally, as for this bit about entries: "worrying if you will be scolded for something you find funny and/or worthy of an entry." While I have seen some mods, at times, act in ways that I question pertaining to entries, the large majority of this unfriendly behavior comes from non-mods. I'm not saying that that makes it okay for mods to act this way, of course, but this is a general user issue. We even added this part to the rules: "Content posted with the aim to slander other posters or the entry poster (such as OP is a Faggot) is disallowed. Content posted with ulterior motives or for public shaming will be dealt with severely, and will lead to suspensions and eventually bans." to try and deal with this.