Just to clarify, you don't need to give every signal a name, just the signal beyond the interlocking, and even then, only when using the "Advanced" mode. That being said, it's probably good form to name each one as signals serve as milepost markers on real railroads, and naming them will cause them to appear in the minimap.
Also, I believe the half-bridges you are referring to are called cantilever bridges. There are a few on the DLS by b9--kiwi and jjslll54 that would work, though you'd probably want to use the catenary/gantry version of my signals for that.
@jordon-The reason there are no left-hand signals because AFAIK the N&W didn't use left-hand signals, at least not often. If you know of any, I'll upload a modified version for left-hand running.