Not always. eg. The Worf books speculated that Worf's human brother was Simon Rozhenko, but the episodes later revealed him to be called Nikolai. You can't assume that every author of regular novels was also reading all the YA books.
Well that's just like with "Survivors"; there was no mention of Tasha's sister in the book, because Ishara had not been introduced on the show yet. But for the most part the Academy books (except for Troi's book) don't really conflict with the other books or the show.
I'm currently finishing up The Buried Age (a lot of it I don't agree with in terms of the age of the galaxy and the evolution stuff, but this is not the time or the place to get into the whole debate on Creation vs. Evolution and the 7,000 year-old theory vs. the millions-of-years-old theory), but Tasha's finally shown up---after the 300th page, and only briefly. I was kind of hoping that she'd be in the story more. Well, maybe in the future we'll get a novel that does have a lot of Tasha Yar in it.
There is no "theory" that the universe is 7000 years old. There isn't really even a hypothesis. People throw the word "theory" around, usually with the modifier "just," to try to debase the word, but "theory" carries with it the rigor of probability and some scientific backing for it. The notion that the universe is 7000 years old has nothing even remotely resembling a basis in science, and is wholly faith based. By definition, faith has no scientific rigor behind it. My objection here is not to faith, nor do I mean to belittle anyone's faith. My objection is linguistic -- tomswift2002's use of the word "theory" is dangerously, insultingly wrong.
^Right. A theory is a model of a process or set of processes proposed to explain an observed body of data, and explaining them in a way that makes predictions that can be used to test the accuracy of the model. Things like the age of the Earth, the age of the universe, and the process of genetic change from one species to another are not theories; they are data. They are measurements and observations that have been verified countless ways. The theories are the models that explain how those measured results came about and what they can predict about new measurements. There is such a thing as music theory and color theory, but that doesn't mean the existence of music and color are unproven. The theories are not the assertion that the things exist, since that is an observed result; rather, they are the models explaining how they work and what processes underlie them.