There is a big world out there. I strongly suggest that you explore it. I love railroading, and have a hard time imaging working in some other field. With this said, it is not a land of lollypops, mermaids, and unicorns.
Railroading is still a tough and sometimes dangerous occupation. One slip up might get you injured, or even killed. You have to concentrate always. Never mind that old Alco, which is dead in tow, bound for some short line.
Traffic levels are also dependent on the season, weather, and economy. Having some other skill might be helpful. It is often several years before you will work year round. Even passenger service is not immune. Most passenger carriers are government funded. Look at 2008, where even the government was cutting funding to certain programs. The Tea Party is always trying to cut Amtrak funding. With little seniority, you would be the first cut off.
One other thought is retirement. You have to work to age 60. That means 42 years service (sentence). I hired at 25, and have to work almost 5 years past my 30 years service. The good side is that I have some extra time, in case something happens, I will not have to work to 65+, for example.
You are young get an education, and not just in school. Meet some girls. Few will put up with the fact that even in passenger, your low seniority will put you on the job with nights and weekends. Some friends will stop calling because you have to say no too many times to plans, or they are afraid to disturb your sleep.
You want passenger. Most commuter carriers pay pretty high, but look at how much it costs to live in a city like New York, Chicago, or Boston. This is where I got really lucky. My first job was on BN, in Aurora, IL. There I could work freight or passenger. I got cut off and had to move to Galesburg. This meant all freight work, but my expenses were cut in half. Rent was cheaper, and even auto insurance. My money went much further. The freight jobs which my seniority allowed were better paying than passenger.
You will not be Casey Jones on day one, as has been explained to you. I feel that a good railroading knowledge is beneficial to being a successful engineer anyway. The more varied jobs you work, the better. I also don't think that this knowledge is gained too well sitting inside a coach. A friend of mine switched to Amtrak. He says setting out a crippled car is a federal project to the passenger trainmen, while anyone who has set a car out in freight would already be on the move, even with the extra steps of disconnecting the 480v. lines.
It looks like a good soul searching in in order for you. I went to a state college. Many of my classmates were on a free ride, thanks to the National Guard. Use this path to full advantage for college or vocational training. Most other railroad crafts have skills which are useful outside the railroad. T&E service does not.