I'm sorry - how can you say a school is the most "desirable" in the area if you haven't visited it!!
It could be completely wrong for your son, so how can he want to go there if he hasn't ever been. Don't get me wrong, I am very happy with the school for my boys but EVERY school feels very different - it is not just about how difficult it is to get in or the results - it has a completely different feel to Alcester Grammar School for example (and Shottery for that matter - and not just because it is all boys!) We know people who walked into KES on an Open Day and walked out hating it, but conversely loved AGS....we felt the opposite - a school is so much more than results and where people perceive its' local standing is...!
KES does not suit everyone - some friends describe it as a marmite school - you may be one of the ones who hate it. However, although I genuinely think it is ridiculous to entertain a school that you have never visited, I will endeavour to answer your questions:
KES have high expectations that all boys will try their hardest and work hard. Like any school there are boys who are brilliant at some subjects, find others harder and a majority who are just generally good at all of them. Not doing homework is a cardinal sin and massively frowned upon and will result in detentions! High standards are expected in all areas of the school. Boys are tracked constantly so that everyone can see if they are ahead of challenge grades, on target or below target. There are a number of ways they are supported if they need help - lunchtime clubs, academic mentors etc - regular testing in all subjects goes on - boys are expected to try hard and achieve well and test results are reported back to parents at parents evenings - I am aware of occasions where some boys were required to resit a Latin exam as they had done poorly.
So how is it handled? The support is there in spades but equally KES expects your boy to put the effort in and work harder at subjects he finds tricky. Hard work and effort are rewarded.
Sport is a huge part of life at KES and 50-75% of each year group regularly represent the school in some sport or another, but there are boys who are not so good at sport (James Dean will always cite their DS as this but actually he loves participating!!) but brilliant at drama or brilliant at music, so your son can flourish in another arena.
Convenience of a school is important but think carefully about applying for a school that you know very little about - your son's score may indicate that he is able enough but the school may not be the best fit for him. What school were you considering before the results came out - or has he always wanted to go to KES yet you never took him to look round?