Walls and Ceilings - Need help with hanging drywall on ceiling and walls!!

I'm starting to drywall my unfinished basement and am seeking advice on some general questions. First, though, I should mention that I have 8' ceilings, a 5 1/2" ledge that goes around the outside walls of the house only (the ledge is 4'10" from the ceiling and 3'2" from the floor), and I have 2 bedrooms, a bathroom, and a living space to rock. In total, there is about 1,100 square feet. My questions are as follows:

1) Is it best to hang the drywall vertically or horizontally on both the ceilings and walls and why?
2) Is it best to use one common length of drywall all around for the ceilings and walls or a combination of, for example, 8' and 12' sheets?
3) Is it best to measure and pre-cut the outlets, receptacles, lights, etc. before hanging or use a power tool such as a Rotozip after hanging?
4) For door frames, is it best to pre-cut the opening or hang the drywall and cut after it's secure?
5) How many screws should be used on a typical piece of drywall and how far apart should they be?

Any help is appreciated!!

#1 - it is usually best to hang horizontally on the wall as it makes finishing easier and spreads the flat sheet over more studs which helps the wall to appear straighter. In your case it might be better to hang vertically. I would go with whichever method is more economical.
The ceiling should span the rafters/joists. Again hanging the rock perpindicular to the framing helps to make a level ceiling. Always stagger the joints.

#2 - it's always better to use the longest piece you can work with. Longer = less joints.

#3 - the pros use a router to cut around the boxes after the rock is hung. I have better results measuring CAREFULLY and pre cutting.

#4 - hang the board first, then cut

#5 - I usually screw/nail every 8"-12" around the perimeter and goups of 2 every 16" in the centers.