If you were born on an airplane where would you be born?
On an airplane.
That very much depends on what you want it to do.. For a graceful kind of glider I would recommend the Floating Paper airplane. For a fast kind of dart I would recommend the Bottlenose Paper airplane. For a good all-rounder I would recommend the Rapier paper airplane. Instructions are linked below for making these.
If there were a thousand seaguls in an airplane while its flying each weighing two pounds a piece but they were all flying in the airplane would the airplane weigh 2000 pounds more?
Without thrust, the airplane would never move forward, and without lift, it would never get off the ground. It would seem therefore, that these forces are absolutely essential to the realization of the entire notion of "airplane", since without them, it would be absurd for the pathetic craft to attempt to lay claim to the title.