Earthquake Valve Installation Help Needed

Two questions ...

1)  Do I have to use Black Iron when doing exterior gas work or can I use
Galvanized?

2)  The EV I am planning on using is only going to be mounted about 4" from
the house and it
      is too tight to turn the meter to tighten it.  Can I use a union
fitting on either side of the
      the feed.  Can I use union fittings on either side of it?