Jack,  I have a 48-note Piano Melodico, so cannot answer all of your
questions.  The instrument action was patented in 1887.  Mine is serial
number 6278 and was told from the Racca museum that it would date
around 1906.  That may help date yours.  I did not find any dates
written inside.   As far as weight goes, it's going to be like a very
nice, very large music box.  So any sturdy table will hold it.

If you have not yet viewed Dr. Christian F. C. Greinacher's article in
the COAA archives, you might want to read it:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&ved=2ahUKEwjZlaelsOXkAhUEF6wKHbiKCEYQFjALegQIAhAC&url=http%3A%2F%2Fwww.coaa.us%2Findex_archive%2FIssues_11_to_20%2FPiano%2520Melodico%2520%25E2%2580%2594%2520A%2520family%2520of%2520Mechanical%2520Musical%2520Instruments_Christian%2520Greinacher__14%2520%2520Giovanni%2520Racca.pdf&usg=AOvVaw1CSevdX1aQXLv5Ex_rwZa_ 

He was a tremendous help and can be reached at c.greinacher@t-online.de.geentroep [delete ".geentroep" to reply]

I tried the Piano Melodico G. Racca Club, but I didn't get much of a
response: http://www.pianomelodico.com/english/feedback.htm 

Another contact was Giovanni Vitiello in Italy.  He was able to help.
His email is  giovanni.celestino@gmail.com.geentroep [delete
".geentroep" to reply]

Yes, all of the music I have is opera.

Jim Quashnock