My suggestion is to give us the option in which chronological order to have the unanswered questions presented. For example, on the bar when clicking the "unanswered" tab presenting us with the further options of "newest to oldest" and "oldest to newest". Because especially in math, most old questions that remain unanswered, are in fact open problems that have been looked at hundreds of times. So it is more beneficial to have the quick option to see questions from a certain period or the newest ones.
In general I agree in adding more options as buttons rather than having to add long lines of code in our search bar for the more intricate options. For example, similar to google's "Tools", creating an advanced search tab containing many options to choose from.