I'm in no way connected with Progressive Industries, but I can tell you that I have the hardwired 50A unit sitting on my desk, and it does have a remote display.
There are two versions of the hardwired 50A unit, one with, and one without the remote display.
If you look at the chart you will see that the EMS-HW50C has the remote display, and the EMS-LHC50C has a display built in.
I cannot address the reverse polarity issue, except to state that the Progressive Industries Web Site states "If AC power is a reverse polarity condition, the EMS will not allow power to the RV and the error code will read E-1."
I do not plan to "test" this feature, but would find it hard to believe that a manufacturer would explicitly state that, and it not be true.