1. Look out the window of a plane at 35,000 feet, you can see it...with your own eyes.  
2. I already gave you the explanation. You are the doubter. Its your job to provide tested proof.  But if you need more, navigators have long had to account for curvature to get where they are going over sea.
3.  The earth is not a "vacuum package".  Its a object existing in an infinite vacuum, with enough gravity to keep a bit of gas close to the surface.  Your metaphor is faulty.

But you didn't read my link did you?  That would indicate you aren't actually open to a discussion but just want to reinforce your homo-centric point of view. So, ta ta.