Welcome rocket, lurk no more 
Starting with your last question, Statemented children jump to the top of the queue for school places. It won't matter how many children want a place, if the school is right for your DS, he'll get a place prioritised.
Secondly, if a school tries to put you off, it will tell you a lot about their attitude!
My first choice MS school, when I went to visit, treated DD1 with utter ignorance and stressed how much provision I needed to get in a statement 'or they wouldn't be able to help her'.
The MS school I thought I wouldn't like, treated DD1 like a queen. They told me to do my best with a statement, but don't worry, they'd give her what she needed anyway, and in fact they were funding full 1:1 for a child while they sorted a statement out for them because they'd come to school without one. They also invited me to come in and see the SENCO to discuss DD1 (it was November) so that the school could start thinking of what she'd need for September and how they could sort it all out.
As it happens, the LA offered her a Special School place in the end.