I made a real cute Santa and sleigh, etc.  Then I decided to have him fly over the world.  Well, I got the world under him --- but I had to pull it wayyyyyyyyyy down below the floor.  When I render it looks cool -- but in the preview the shadow of the world is at floor level and the world is below.

I thought about this for a long time because I didn't want to mess with all the Santa stuff.  Too many objects to try to raise.  

1. How can I lower the floor?          This would make the world above the floor line and the shadow wouldn't show -- I hope.

2.  In the preview, the shadow shows.  In the full render it doesn't.  But when I print out the render it prints the preview and the shadow is there again.  Why?

3.  Also, my background was white and then I added an object and it turned dark.  So I made the lighting "daylight" and the color is good -- and white in the preview.   In the render it is a light green.    Why does the render look different than the preview? 

4.  Any ideas how to add a night sky without making it too dark?

Thanks so much in advance. 
Bev