You can measure the curvature of the earth yourself.  Don't be satisfied with just being a keyboard warrior. Go do the experiment yourself. Don't trust, verify. 

Something in orbit doesn't use fuel, it's just continually "falling". To get into space, rocket fuel includes an oxidizer to allow combustion in a vacuum. This is like super well known and understood science.

Have a nice day! Stay away from the edge of the planet 😉