Alright, see if I can answer everything at once;
Guards can see one another, as the are at opposite ends of a straight hallway about 50' long. Both are human, both armed with Ares Alpha assault rifles, both have smart links, one had a full cyber arm where his left used to be. Both appear to be wired, but can't quite tell how extensively, looks like bone lacing and wired reflexes of some rating. They don't have any internal comm system, but are both wearing headsets.
To my understanding, and please correct me if I'm wrong, a spirit's concealment power does not make you fully invisible, but rather uses the environment it is attuned to to mask you? In which case, that alone would not be enough to get you down the hall undetected. But would be able to help with other abilities.