When you graduate and decide to sail on your license you can live anywhere you want, including in NYC. It is most convenient when starting your career to live near a union hall because you will have to appear at the hall in person to get a ship, at least until you become established in the industry. Most commonly you will work something like 3-4 months on and 3-4 months off. The shipping company will fly you to wherever you are picking up your ship then fly you back to your home base when you get off the ship. So it does not matter where you live. If you want to fulfill your obligation and sail locally in NYC, you can always work on the ferry system and come come every night. The possibilities are many depending on your priorities.
The effects of the Baltimore tragedy are obviously huge in the short term because of the amount of ship traffic in that port. However, every effort will be made to reopen that port as soon as possible, so long term effects will be little to none.