Disklavier

Hi, I'm new here. Would like to start with some basic questions. 
Tried going through the site...see most of the issues are pretty 
advanced, so would really appreciate your patience to help me with 
some basic stuff.

1. Type of Disklavier

My understanding: 
i. 1st Gen = Pianosoft Solo disks only, 3.5" Floppy DD only. 
ii. 2nd Gen = Mark II XG = Pianosoft Plus disks, 3.5" Floppy HD 
disks.
iii. 3rd Gen - Mark III = CD playable.

Am I right? Or far off?

2. See quite a few people have added the CD Player DCD1 to the older 
disklaviers.

i. What's the cost of the DCD1?
ii. Does it make Pianosoft Plus/Smart CDs to be playable on older 
disklaviers, or make 1st Gen Disklavier become XG?

3. Files sharing.

Those files available for download...how do you play them on the 
disklavier? Copy to a 3.5" floppy DD or HD? Someone mentioned 
disklavier can be connected to a computer to play the MIDI 
files...did I get understand it right?

4. I should be ordering a used disklavier 121 or 131cm height within 
a week, imported from Japan. Any advice?

Thanks in advance.