You can definitely leave luggage there, but not sure about few days - better contact hotel staff directly, they have English speaking staff so should not be problematic.

Yes, I had an in room massage about 1 month ago. The masseuse was really good about digging in where I was tight. Do not have an expectation that this is like a resort spa relaxing massage. This is good for actually working out kinks in your muscles.

2pm

Yes. Sale I think 3000 or 3300 yen. It has the Limusine Bus, which is very good.