Can anti matter be specific (like anti water, anti iron)?
Yes. AntiHydrogen and AntiHelium are all we can make in any significant quantities here on Earth (see AEgIS, alpha-G and G-bar project notes), but in an area of suitably dense antimatter, we would expect all of the anti-atoms to form an anti-periodic table of the exact same stability (since positive and negative charges are arbitrary distinctions, in the absence of lots of the opposite).
We cannot tell if galaxies that are far away are made of matter or antimatter by their absorption signatures, because the lines are exactly the same (see confirmation for antiHydrogen here: Observation of the hyperfine spectrum of antihydrogen ). The furthest Voyager 1 has gone and reported back is 0.0000006 Mpc, and our light cone goes thousands of Mpc, so the extrapolation we make of our local matter antimatter ratio to the whole light cone is just plain stupid.