Disklavier

I'm a bit new to this disklavier thing on my Yamaha baby grand but am
enjoying it immensely.  The guy I bought it from included a few disks of
various types of music, and now I am looking to get some more, so questions:

 

1. Going to pianosoft.com it asks what model disklavier I have.  Looking at
the bottom of my unit, it says "DA1-II" by model which does not appear to be
one of the choices in the drop-down box at that site?

 

2. Is there a better (read "cheaper") place to get disks than pianosoft.com?

 

3. One of the disks that was included when I bought it (which of course now
I can't find) was pretty cool - it was jazz with string bass and drums, and
the previous owner showed me how to shut off the right channel so that the
piano was *muted* only leaving the string bass and drums, allowing one to
jam with it.  How do I find disks that have a similar string bass/drums or
other instruments along with the piano where I could shut off the piano
channel and play along with the rest of it?

 

Thanks

Jon