I know what you mean. A friend of mine lost 50% of her business when her sone never got into the primary school she had been dropping off/collecting at, even though he was in catchement. It was an oversubscribed year so they drew the circle closer.
Yes it would - but only if that's actually stated in the school's admission criteria- and if it is, obviously places would go to children IN catchment AND at a feeder before your DC, sadly. You should be able to get the trend figure from the school, as in how far 'down the list' they accepted in previous years though of course this guarantees nothing THIS year.
Have you asked the school directly what your DCs chance of a place is?
When we chose a Secondary school for DD1 last year I had heard all the usual local rumours about not getting in etc. I asked the headteacher on the open day what the chances of getting a place were and when he found out our address he said we would be guaranteed a place and although they were usually over subscribed, he then went on to list the towns (huge catchment are) which were borderline.