As to what will happen if you tick the 'yes' boxes, you WILL have an interview with immigration (not customs - they deal with baggage) - it's called being referred for secondary questioning. The same will happen if you tick the 'no' boxes and they sus out, or know, you are lying.
If they decide to refuse you entry, the best that will happen is that you will be escorted straight back to a plane and sent home. You will not be allowed to see the rest of your family. The airline will later bill you for the fare.
If there's no available flight, you will be kept in a cell, probably shackled, until there is one.