is it possible to park luggage at the cloakroom while visiting museum?
RS's 'Italy 2011' says "Bag check is obligatory and free", although I don't know just how large a bag they're prepared to take...I'd assume 'regular-sized' bags. There is an email form at the bottom of their website; I'd suggest writing them and give them the number and dimensions (inches and centimeters) of each bag. Then, BRING a copy of their email response, if it's favorable - IF you get one! - and show it to them if there's any trouble. I'm also pretty positive you can check luggage at the Centrale train station... Yes, it's €4/5 hours, then €0.60/hour after that, daily 7:00-23:00 near track 5 ("deposito bagagli"). Have fun!
grazie!