7) First computer to sell more than 1,000 
One of the S/360s went into the four digits. I am not sure which one
(model 40?). 1401s may have beaten though.
  8) "        "                "
"    "        "        10,000 
PDP-8, probably.
  9) First computer to use a floppy disk (any kind of
floppy) 
One of the device controllers for the S/360s. The original intent of the
floppy was to distribute microcode updates.
William Donzelli
william(a)ans.net