Are the purchasable costumes restricted to the relevant faction?, for example a federation costume (say section 31 uniform) on my romulan character, while on that char looking at it ingame it dosent actually say in the info "can not use" but I want to ask before I buy anything to be sure, ty.
Unless the description says 'Can Be Used', its best to assume that they can't be used by other factions. As an Example, the '7 of 9' outfit does not say 'Can't be Used' with Female Liberated Romulan Characters, but its unavailable for my Liberated Romulan character...
Romulan faction characters can only use Romulan faction uniforms. As you go through the storyline and complete the episode "Turning Point" to choose your ally, you get Fed/KDF uniforms that are based on your chosen ally's.
So for example, Romulan faction character's can't use the Section 31, TNG, Enterprise, 7of9, or KDF academy, etc., uniforms from the C-store. The only uniforms in the C-store they can use are the 2 Romulan faction specific, but the Reman uniform in the C-store can only be used on Reman characters.
However, if you have bridge officers from your allied faction, such as a Human or Vulcan when allied with Fed, they can use only your allied faction's uniforms, even C-store outfits. (with the exclusion of off duty wear of course.)