9x18

They could just be "land rich". The Apple family has both the ability and means to provide for themselves, but it may bot translate into a substantial amount of money - plenty to cover their needs and a little more, but not enough to do Scrooge McDuck backflips into.

I agree with the assumption that the five small stars are about friendship/elements of harmony - seems pretty straightforward. The base part of the cutie mark, the six-pointed star, could be some family representation of magic. Shining Armor's mark has the same star. The insignia he wore in A Canterlot Wedding also bears the same symbol, and it belonged to his "favorite uncle". Parents don't seem to have it, though.

Couple of good ones from Ponyville Confidential: The same cake design appears at the competition near Celestia in MMMystery on the Friendship Express. Time-traveling photographer? ..and a nice faceplant into Twilight's force field.

Oh lawd I'm Apple Bloom - what were the odds. At least my sister would be best pony Galloping Pie would be a funny one. Apples apples apples.

Pretty much this. I'm uneasy about how they made the change, but I'll reserve judgement for Season 4 once they have a chance to work with it.

Traits associated with the Autism spectrum that go along with those I mentioned include things such as difficulty with social expectations, picking up on expressions / being expressive, etc. I have no observed Twilight having consistent difficulty with any of those. As a filly (during the entrance exam, for example), Twilight's expressiveness, eye contact, interaction, communication, etc. was certainly neurotypical and does not appear to be consistent with AS; at least, nothing jumps out. I briefly mentioned these traits before, but my apologies if I was not clear why I mentioned these aspects. Poor working memory is also very common with the personality type I claim she fits to - it could just as easily be explained with this. I do not think her list-making is routine for routine's sake, but only routine because it is a recognized necessity. I'm going to half-disagree with this. The series is about Twilight making friends, which requires socialization - the two are not mutually inclusive or exclusive. Twilight's socialization behavior is completely typical of a introverted thinking individual (aforementioned personality types). When socializing, there is disinterest which can be perceived as awkwardness. This is because she does not want to be there (again, for the aforementioned reasons of mental stimulation), but I observe no difficulty in the sense that she does not know how to interact with others when forced to do so. My explanation from this comes from the perspective of someone with a similar personality. I suppose the AS vs. introvert would hinge on inability to interact with others in neurotypical fashion vs. has no desire to interact with others, respectively. I'm leaning to the latter. I was not familiar with OCPD. After doing a quick read on the subject, I agree with an assessment of OCPD.

I disagree with the idea that Twilight may have Asperger's. Her personality is very typical of a scholarly introvert, and is very close to that of a stereotypical INT_ personality. These personality types do have a number of traits that overlap with Asperger's, but there are key differences, particularly with respect to social cues, protocol, and expression. Here's my take on some of the behaviors brought up thus far: List Making Lists serve simply as a reminder to ensure everything is complete. It isn't to help ease the stress of managing things, compulsion to follow a ritual, etc. For someone in their own head constantly, items which need to be done can pop up and be forgotten quickly. Making a list is just a method to help with this type of forgetfulness. Socializing Preferring not to socialize does not necessarily indicate that she has a personal difficulty with, or aversion to, socializiation per se. As we can see, she has no problem interacting regularly with her close friends in what many would consider a normal or typical manner. Her type of personality demands mental stimulation; this is not provided (or expected to be provided) by small talk or chatting with random individuals. I'm pulling this bit from memory, but if I recall correctly, even in social situations we see her with a book on more than one occasion. Time alone with thoughts is her type of relaxation. OCD She may have mild OCD. First thing that pops into my head is in "Spike at Your Service", Applejack gets Twilight's attention by moving the ink well. Twilight not only reacts immediately to that and acknowledges Applejack's presence, but also quickly moves the ink well back to its proper position. There was nothing inherently wrong with the ink well's new position; it remained functional and appropriately located for use. "Lesson Zero" catches some of it as well. The deadline for the letter was mostly self-imposed. Like with the ink well's position, it seems atypical for Twilight's logical personality to place so much emphasis on something which really has no meaning, if you will.

Ah, pony genealogy. There was a program out there at one point called Family Tree Maker - it has been around many years, and you may be able to find one of the older versions available for free.