About just who's an alchemist among the Boys in Blue...
Myself, I have been assuming that only Roy is an alchemist. Certainly none of the others are introduced with the kind of "call sign" that Roy and Ed have. My thought was that becoming a State/National Alchemist drafts a person into the military as a sort of auxilliary, thus the constant comments about them being "dogs of the military". Roy, by this reasoning, takes advantage of this fact and works for promotion to Colonel in addition to his status as Alchemist, making Hawkeye and Havoc his military staff. Neither they, nor Hughs, who looks to be in Intelligence to me, give any indication of alchemical ability, Hawkeye, for example, defaulting to her gun when that train-jacker attacks Roy.
It's the "call sign" that especially inclines me this way, since all those we know are Alchemists are known in that particular way.
As to why Ed, now inducted to the military, does not wear the uniform... well, it's Ed.
By the way, do people hereabouts prefer heavy cut-tag use? Just personally, I can't stand it and only use it when I'm really, really running on, but I can certainly use it more here if everyone prefers.