Correct, but all EI flights depart from the B Concourse, which does have the facility. AA use this concourse too. Not sure about Delta or Continental.
The DL/CO flights normally go from the B concourse.
Sometimes there is a "late" EI flight at 1740 from DUB to JFK that doesn't clear immigration in Dublin but in JFK as they only keep the US immigration post open until 1500
That's correct. No pre-clearance for the late evening flight!