Are 4x8 sheets of drywall actually 48" X 96"? If so it looks like I'll have
to cut some off every sheet.

Yes they are. My basement (mainly unfinished) ceiling height is 9 ft and I
got a great deal on some 5/8" firerock (20+ 10 ft sheets @ $ 1.00 each)
There was water damage on one corner where a tarp had let water leak onto
the pile (they had ~400 sheets like that). I ve cut one foot off the length
to 9 ft and will hang them vertically. I already set the electrical boxes
for the 5/8.

Regular 8' sheets here (Canada) are about double what they sell for in the
US $ 11.96 vs About $ 6.38 !!
We re being ROBBED by CSG, a division of USG Sheetrock. The boxes of
"mud" are a rip-off too $ 14.00 VS around 6 bucks so I buy the 'mud' down
in Washington state.