Concerning the discounts, you have to check the individual museum/attraction websites for "concessions" or "reduced" ticketing. For instance, Musei Capitolini? The "Concessions and Free Admissions" page of their websites states:
"Concessionary fares (for which will be issued a concessionary ticket), are available for....
...Roma Pass holders, when visiting the third museums and/or archaeological sites onwards."
A "reduced" ticket - which I take to be "concession" price - looks to be just 2 euro less than a regularly priced ticket.
http://en.museicapitolini.org/informazioni_pratiche/biglietti_e_videoguide
It can take some digging around, it's not always spelled out clearly, and that's a personal annoyance about the Roma Pass website. We've not used the pass as the transport piece wasn't a big enough benefit for us.