A round window in the hull (originally any opening in the hull) is called a porthole. A window in the superstructure is a window.
It is called a brig.
Tack
The Mongolia
He sailed aboard a ship called "Welcome".
same as on a ship, the galley
Still a cook - but the kitchen is a galley
Stowaway
Yes
It is about 103 people aboard the Mayflower ship!
* porthole
they came aboard on the ship to go to the island.
It was called steerage.