During the Kingdom of Italy (1861-1946) the Princes of the Royal Family were styled either His/Her Royal Highness or His/Her Serene Highness, accordingly to a Royal Decree issued in 1890 (although applied with many exceptions).
The other non-Royal Princes were styled either His/Her Serene Highness (mainly the Princes whose title was created by the Holy Roman Emperor and then recognized by the Kingdom of Italy - i.e. the Princes della Torre e Tasso or the Princes Gonzaga) or His/Her Excellency.
As for your second question, you can find a list of (many of) the Italian noble families in the Annuario della Nobiltà Italiana (Yearbook of Italian Nobility); I have find some lists of surname of noble families taken from the Annuario:
(Some of the) Noble families whose titles were recognized/conferred by the King of Italy:
https://docs.google.com/viewer?a=v&...pbnxjbHViYW5ub2JpdHxneDoxZmM5YjUwNjFiOWU0N2U2
Noble families whose titles were conferred by the Sovereign Military Order of Malta:
https://docs.google.com/viewer?a=v&...WFpbnxjbHViYW5ub2JpdHxneDo3YTJmZTExMDFhMDUyYw
Noble families whose titles were conferred by King Umberto II of Italy during his exile:
https://docs.google.com/viewer?a=v&...pbnxjbHViYW5ub2JpdHxneDoyYmQ3NjBlNTJhNDMzZmYx