"Educative" is a synonym for "pedagogical", or "didactic", which means it teaches other people something significant, interesting, or otherwise important knowledge.
"Insightful" is an adjective which says that someone's work has brought light, new understanding, or a new perspective to the topic at hand; it may not actually teach anyone anything, though, because it may already be re-hashing established knowledge (as when a student prepares a term paper for a teacher), or it may simply be re-introducing knowledge or a topic from a new, hitherto unexplored angle (as often happens with poetry, good literary and arts criticism, and so on).
So the answer is: this depends on what you want to emphasize. Do you want to say people can learn a lot from this article? Or do you want to say that the article just gives people a new perspective on something?
Obviously, a well-written article can be both educative and insightful; the two ideas do share some overlap, and in some instances can be used interchangeably. One must make sure, however, that both meanings are intended, because not all educative works are insightful (think a basic reader for first-graders), and not all insightful works are educative (think of a comedic piece by Richard Pryor, or Bill Hicks).
The "uncomfortable sound" of the example is due to the clash, or lack of parallelism, of "many questions are" with (in effect) "not every question is". The problem can't be fixed just by substituting something for "questions" and something for "are"; instead, rewrites along the following lines are needed:
Many questions (if not every question) ... are answered.
Many (if not all) questions ... are answered.
All but a small number of questions ... are answered.
All of these are correct forms. The first one still has a difference in number between the main subject and the parenthesized one, but with parallelism more properly established than in the original sentence, that problem of style is less glaring. The second form is quite similar to your original, with all in place of every.
Best Answer
The first thing to say is that you might want to change ‘he’d say he’s curious’ to ‘he’d say he was curious’, because it’s reported speech.
‘And then forget’ is an ellipsed form of ‘And then he would forget . . .’ and there’s nothing grammatically wrong with it (‘then’ can come before or after ‘would’).
In the example
the tenses are out of sequence. For it to work, you’d have to change the verb forms in the first sentence and say