I am not sure what the letter tells you - hopefully someone else can answer that - but most schools which use score order as part of their admissions policy do state the score in the letter.
However, as far as admissions go, it is not possible to tell how many places will go to candidates out of the catchment area or not attending the feeder schools as this will depend on how many in-area/in-feeder school children pass and choose the school, however, the school estimates that about one third of places go to children outside of the feeder schools - see the admissions policy linked from here:
http://www.kevigs.org/how-to-apply/4570836107I am not sure how much the school would tell you after the closing date for applications at which stage they would have a pretty good idea of numbers as they would know how many in-area/feeder schools children had passed and applied - you could certainly try asking...