Richard Spier's overprotectiveness and high/age-inappropriate standards for Mary Anne's behavior become a lot more understandable after the revelations of Mary Anne and the Secret in the Attic. Not only did he lose his beloved young wife to cancer, but her parents threatened to sue him for custody of their granddaughter if he were deemed "unfit" as a parent. No wonder he went overboard in raising a sweet, demure young woman who's too meek for her own good.
That said, there is his childhood in a working-class family and being misjudged by Sharon's upper class parents... especially when you consider that Stoneybrook seems to be a affluent community (middle-class at the least). The class-based prejudice must have done a number on his sense of self and made him feel like people were constantly judging him, which could also add to his fear of being deemed/perceived as an unfit parent.
Claudia's grandmother Mimi could be considered to have a Meaningful Name in her native language, Japanese. "Mimi" in Japanese means "ear", and especially in the beginning of the series, Mimi was the family member who Claudia could count on to listen to her and be understanding of her problems.
In the final scene of Mallory and the Ghost Cat, the family notes that the strange meowing-like noise from their attic seems to have disappeared after they adopted a cat from the shelter. Seems spooky — except that the family adopted a deaf cat, and deaf cats tend to be especially vocal (and much louder with those vocalizations) because they can't hear themselves. They're probably just not hearing the noise anymore because their real cat is noisy enough that they don't hear it, or if they do they just assume it's her.
Look at the age gaps between the Thomas siblings. There are two years between Charlie and Sam, and two/three years between Sam and Kristy, but about six years between Kristy and David Michael. Then consider the fact that Patrick walked out on his wife and kids not long after David Michael was born. This suggests one of two scenarios: either David Michael was an 'Ooops' baby and Patrick couldn't deal with the additional responsibility, or the marriage was already rocky and it was a case of "let's have another baby to save our marriage" that didn't work out and if anything made things worse. This would also explain Patrick basically refusing to acknowledge David Michael's existence, as either way he might feel resentment towards him for causing the end of/not saving the marriage (as well as potentially guilt in the latter case for choosing to have him when he wasn't ready to deal with another kid).
The original series started as just a four book contract that expanded past when it became popular and had updated cover reprints later on. Similarly, the comic book series started as just a four book contract and when it became popular, the first four books were reprinted in color.
From the graphic novels: in Stacey's Mistake, Dawn's postcard is addressed to her brother Jeff in California, while everyone else's cards are sent to the recipient or recipients' home address. It could be thought that he's on vacation for some reason, but only later in the novel does Dawn reveals he's since moved back to California for good.
