As the number of my favorite questions increase, it becomes harder to find them in the list. Is there a way to search in my favorite questions?
Also, would it be possible to search in another user's favorite questions?
You can use the normal search with the specification "infavorites:mine". When you are viewing search results, look at the "Advanced Search Tips" to the right of the search input field.
To search in someone else's favorites, use "infavorites:13854" where 13854 is replaced with the person's MSE id.