Moving between Passages is easy!
At the top of each page in the Catacombs is a set of buttons that are clearly labeled for each passage. Simply click the Passage you wish to visit and immediately you'll be transported there.
Keeping track of where you are is equally as easy. At the top of the page, the Passage button will change to indicate where you currently are.
As an example, if you're in Passage 1, the button for this area will say "You Are Here", and that button will then remain unclickable until you move to another location.