Answer:
Yes, it is alright!!! Don't worry too much! Everything will turn out great:))
A three dimensional affect.
Answer:
Because the earth is so large that smaller things like the floor, or even a whole city appear to be unchanged when you look at it, but from a large distance, namely space it is most definetely round.
It will take between 5-45 days
Usually you control your exposure using aperture, shutter speed, and ISO; too much light is not usually a problem, because you can find an acceptable combination of the above to give the proper exposure even in the most intense sunlight. Most people have the opposite problem, too little light.
Sometimes for artistic reasons you can't adjust one of those parameters into submission. One common example is using a very long shutter time to get a smooth water effect for a waterfall. In that case you can use a neutral density filter to cut the amount of light coming into the camera.