Just thought I'd throw in a bit of what I use as a conductor. I wear Carhartt bibs year round (comfortable, plus all the other benefits mentioned), and usually have a Dickies button down shirt underneath (long or short depending on season). Canadian Pacific requires full safety boots (and I would want them anyway). For my foot I've had multiple pairs of the same
Terra model, which I keep well waterproofed with dubbin at all times (waterproofs and keeps muck from fouling the leather and wearing it out early). Other PPE is provided by the railroad.
I also prefer to have my radio in a holster on a belt (instead of the vest pocket --- where the clip-mic cable always hangs too loose and creates IMHO a major snagging hazard), and on that same belt I have another small Kuny's pouch that I can stash my pliers, crayon, and whatever in (just easier to throw that on than to always have my pockets full of tools I don't need --- plus I only need to grab "one thing" if I'm walking back suspecting a knuckle.
My grip is the one from Red Oxx that was mentioned before. It really is entirely worth the money! Great volume, easy to keep organised/accessible, and durable doesn't even begin to describe it. They are now making a
backpack-style grip for those who prefer that (I may get one myself at some point, been very happy with my standard one).
Outerwear varies widely. I'm in the mountains here, so winter has some pretty harsh requirements. Carhartt is one of a number of good bets. If you are in a place that gets cold I suggest having gear you can layer to get to the proper temp, it's a more flexible approach, and works better than wearing one "fat" layer.
RE: the hickory strip bibs, while I just wear black, many of the other guys in the running trades here wear them. the hats are less common, I can only think of a couple who wear those, and they've been around quite a while. Do yourself a favour and don't go overboard trying to "look like a railroader" when you're starting out. Pocket watches are a pain, but you can get some nice (highly accurate) wrist watches that actually have a "railroad approved" stamp on them (Citizen and Seiko come to mind).
Well...that seems like a sufficiently long first post!