LastResort has got it down.
To answer your original question, no you cannot just slap on 05 STi hubs unless you are using STi rear axles, and R180 rear diff.
Do you have everything else for the 5x114.3 swap?
IMHO it's probably better to just do the fronts with 5x100 rotors and keep your rears stock. Swapping to rear brembos is pretty expensive and probably doesn't make a ton of sense, unless you're doing a full 6-speed/R180 swap.