Hello,
Good luck to you with the hiring process. I think JohnS hit the nail on the head, play stupid. Always ask questions and stay intuitive. If they ask you about safety at the hiring session, its the number one priority, above all else.
From a social point of view. Most the guys I work with hate Foamers and FRN's (F***ing Rail Nuts). Most reasons are personal and unfounded. However, they have been known to cost railroaders their jobs. So I would not mention it to anyone. Likely no one will mention it to you.
As for social media, I have seen people go out, get drunk, post about it or get tagged in a picture. Then get called to work ( I know your under 21 so not an issue right?

). If they blow you and your legally drunk they can fire you on the spot. So best to avoid that kind of stuff.
Also goodluck hiring out. Bad time to be railroading. I've been on and off furloughed for a year. I recommend you look into signal operations of MOW and maybe something with diesel maintenance. Those jobs are likely to stick around even though they pay less.
Also remember this (even if it is negative): Its not a matter of 'if' you get furloughed, but 'when' you get furloughed.
Again goodluck, lets hope business is better by the summer, for both our sakes!
-Jerry