Questions with many downvotes are removed or closed automatically from listings and search results? Are the moderators notified?
When the score of a question is lower than -3, the question is removed from the front page. Questions with many down-votes are still listed, and can be searched. You can search for questions with a score greater or equal to -10.
There aren't automatically closed questions; there are questions that get automatically deleted but only in few cases, such as when the question has 6 flags for being spam or offensive, or it has a negative score and it doesn't have answers, once the question is at least one-month old. More recently, a change about deleting closed questions has been introduced, and it involve questions closed in the past 9 days, when:
The question was not closed as a duplicate - It has a score of zero or less - It is not locked - It has no answers with a score higher than zero - It has no accepted answer - It has no pending reopen votes - It has not been edited in the past nine days