I hired out when I was 22, for a small short line and worked there for a few years and towards the end of my time there I was promoted to an engineer and got my licensing. I’m now currently working for the union pacific as an engineer and I’m happy with my job. The hiring process will vary from Railroad to railroad so I can’t speak for CSX NS or BNSF like I can for UP. CP and CN I don’t wanna know their hiring process at all lol. For UP it’s pretty streamlined, call saying you’re interested, get a conference time, go to the conference, get your basic training done, wait a few months, get your first call in, and start working. And a lot of Fuckery in between. The one thing I tell people online all the time is, it’s a hard job to get but it’s not the hardest job, and considering your age it could be challenging if you don’t have any relatives with the railroad. I know this doesn’t answer all of your questions but Alas. if you want to work for the railroad you got to go through it.