Thanks; lots of great information here.

Regarding duplicates and deletion you may be interested in my thoughts: https://meta.stackoverflow.com/questions/426214/when-is-it-a... ; https://meta.stackoverflow.com/questions/434215/where-do-the... ; https://meta.stackoverflow.com/questions/421677/closing-a-qu... seem relevant here, browsing through a search of my saved posts.

Having duplicates should make the search better, by pointing people who phrase the same problem in different ways to the same place. But low-quality questions often don't produce something searchable for others, and they cover topics relevant to people who lack search skills.