Well, as for the only scientific question on there, the one with the truck and the helium...

A truck would weigh less if it were full of helium than just air...however, if you mean 'empty' as in a 'vacuum', then yes, the vacuum would make the truck weigh less than the helium.

EDIT: Also, a compass will still point to the magnetic south pole of the earth, if it is still close enough to the earth. If the magnetic field of another heavenly object is stronger (ie. closer), it will point to that.