Let me digress a bit and respond just to this part of your question:
It is little embarrassing to know that my stupid answer/question is still visible to so many users.
At least in the case of the questions, they are not "that much visible". Users with 10k+ reputation points can see deleted posts provided they have the link.
So they can find and see your question, for example, if you linked to it in chat or in some your other post, if it is listed on some list (such as favorites or questions that you received a badge for) and in similar situations. And of course, if somebody was interested in your question enough to bookmark the link somewhere, they still have the link and they can see the question. (Assuming they have sufficient reputation.)
10k+ users can also see recent deletions in moderator tools, but self-deletions are not listed there. (So this would only be relevant for a question you did not deleted yourself but which was deleted by roomba or by other users.)
But in general it is very hard (close to impossible) to find a deleted question of another user. The exception are moderators who can search among deleted posts. (You can find your own deleted content - depending on your reputation either only recent ones or all of them. For details see: Is there any way to see my deleted questions or answers? and Can I somewhere see my own deleted questions? But for regular users, the search engine here on site offers no possibility to find deleted stuff posted by others.)
This is somewhat different for answers. If a user views the question and they have sufficient reputation, then they see there both deleted answers and the answers that have not been deleted.