Great questions!
Regarding the Air Powered Racer questions:
Following amendment has been made to rule #4 of the Air Powered Racer.
4. The vehicle must travel a minimum distance of 10.0 meters from being released. The vehicle must remain in contact with the ground during the entire 10 meters of the track. No part of the vehicle should detach from the vehicle during the run or when being released.
Regarding the Marble Coaster question:
Following amendment has been made to rule #3 of the Marble Coaster event.
3. All glue must be dry at the time of competition. Wet glue on the track or on other parts of the coaster will result in disqualification. All parts of the track must be viewable for inspection by the judges.
So, a tunnel would NOT be allowed as part of the marble's track.
Additionally, both corrugated and non-corrugated cardboards will be fine as they're both made of paper.
Hope this helps clarify the rules. Let us know if there are any more questions. We look forward to seeing everyone at the event!