If I remember correctly a 4 day ticket cost 1,400 Yen so a three day is less probably around 1,100, but if you plan to travel back to your room for any reason or head to the city and your hotel is near the resort line, it is very much worth it.

Yes you can. There is enough space. Just remember to take lift to get to the train level.

I believe there are large lockers available suitable for baggages which hopefully yours is of normal size. If its convenient, would be easier to drop them at your hotel first and not have to worry about the baggages later on when you leave. Not sure whether i answered your question. Have a great time in disney. 😃