Dear David,  Greetings from The Bronx.  In regard to what hammers to
purchase, it's not so much the hammer manufacturer, as it is the weight
of the hammer felt -- the heavier the felt, the brighter the sound.
You might want to contact an accomplished piano technician (not just
your run-of-the-mill piano tuner).  They should be savvy in the art of
voicing the hammers, as they would most probably be the best ones to
determine what felt weight to order.  Renner is one of the best known
manufacturers of not just piano hammers, but piano actions and piano
action parts.

As for the selection of MIDI players, there are at least five that come
to mind: Pianocorder (which is no longer being manufactured), Yamaha
Disklavier, PianoDisc, Pianomation (QRS), and the Stahnke reproducing
system (the 'Rolls Royce' of MIDI reproducing systems).

The most readily available systems would be PianoDisc and Pianomation.
Both are available with numerous options, such as wireless operation
and built in synthesizers (PianoDisc) or accompaniment discs
(Pianomation) that feature live orchestras to which the piano plays the
piano part.  Go online and research the system(s) that fills your needs
and expectations.  Hope this helps....

Sincerely,
Dale F. Rowe
Bronx, New York

 [ Another add-on system is Pianoforce -- http://www.pianoforce.com 
 [ Several MMD subscribers are authorized dealers/installers. -- Jody