Hi!
You seal the gap between the flying surfaces (ie wing and ailerons, stab and elevator) with Oracover plastic film Not with tape!!!
Tape works but a much better way of doing it is with a narrow strip (2cm) of Oracover (Ultracote in the US) plastic covering film fastened with an iron.
You do this because to prevent air coming up trough the gap. Air coming up trough the gap will reduce the way the flying surfaces act on the plane. Large gaps and you will have to use large flying surface throws to fly the plane, which is no good. Seal the gap and you can use less throw and the plane will be more responsive.
This is a bad photo but I think you can see the narrow strip of Oracover covering the gap on the underside of the stab of my Viper Q-500 racer.
A much better way than a spinner is to use an aluminium spinner nut.
To start the engine you just turn the rubber cone around.