BRS schedules may look as if they're messed up, but from EZYs point of view (and pax) they seem to work fine, which is the most important thing (makes them a profit) so they won't be changing that in a hurry.
NCL can get up to 8 flights a day from LHR, with some day stopping to make use of cheaper parking here and freeing up space/slots at LHR. Not sure how long this is to last, possibly just until January.
Not all of them go out full (or even half full). Loads tend to fluctuate a lot
They have no plans to permanently add more scheduled flights into NCL at present. They're pretty much making use of parking space elsewhere but offering flights to pax to earn some revenue to make them worthwhile.