We used our credit card just fine when we needed to.

Ciao, in due ore il museo lo giri se corri. Con la guida ce ne vogliono circa tre. La visita con la guida volontaria (in inglese) non c'è bisogno di prenotarla. Una volta comprato il biglietto ed entrati nella parte espositiva del museo, c'è un banchetto con le guide in attesa. Basta andare lì e chiedere se c'è qualcuno disponibile (in giapponese o in inglese).

If I recall correctly not here, cash only.

I already visited the museum. The lockers are small, not suitable for a carry on. But they can store bigger luggage at the ticketing counter by the coin lockers they have a special room for that. 😉

The museum is currently closed until March 2018.

I do not know about another museum. This is certainly a very special exhibition and I do not believe there is a "duplicate". The museum is quite new, so it is really unbelievable that they are closing completely for renovation for such a long period.

I don't think so as the ticket does not have any information of owner. If you want to visit again, please ask the ticketing desk for this situation if they will accept. As Japanese people are so kind to foreigners, it is also possible that they can accept your request.

Would also recommend a minimum of 3 -4 hours and use the free volunteer guide service. But you could - as I did - easily spend a whole day there.