As to the question of what order he belongs to, I would suggest a Windrunner. I forget the exact quote, and I loned my copy of the book in the hopes I could get someone else hooked, but I recall some of the epigraphs about the various orders mentioning relative numbers. I think Windrunners were mentioned as being one of, if not the most common.
This is just wild speculation, but could it be that the proximity to Kaladin as a Radiant, following him as he pursued, to some extent, his ideals, led to them joining his Order. As one of the more combat intensive orders it would be necessary for there to be more of them, so this could be how the Windrunner ranks of old were constantly flooded despite the difficult to uphold ideals. Maybe most of Bridge 4 will become Windrunners and act as the first line of defense?
Something related to this: What does the Stormfather's accepting of a Nahel Bond (if an unconventional one) mean for the honourspren. As I recall, it's been established that a large part of the reason Syl was the only honourspren to return was because the Stormfather forbade it, not wanting the spren, whom he considers his children, to be killed by the bond.