Are Bachmann steel and nickel silver EZ track the same code? Will they work together?
Yes, they are both code 100, and are interchangeable, although steel is not recommended for dcc typically, but some people use it.
The only incompatibility of steel with DCC is letting your track become too dirty. I use nickel-silver, brass and steel interchangeably on my 350 square foot, DCC powered layout and they all work just fine. I clean the rails when I first lay them, then about every 5 years after that. But I oil them right after cleaning and about every 6 months to a year after. All it takes is a very tiny amount of light, conductive oil such as Conductalube or Labelle 108. One or at most two drops will do an entire 4 x 8 layout.
Jim