Are you able to leave and come back?

Covers full access to the museum and the battleships in the cove for 2 days you can come and go as you please during those two days we had went yesterday and still have full access to both locations today but we had finished everything yesterday we left for lunch came back went and viewed more stuff so it's pretty much free access to both locations for the two days during business hours

I think you have two days to visit the battleship Take like 4 hours to ser everything

Yes, on the day of your visit you will be given a tag to wear. That tag is good for that day.