The rule might be unwritten but I have never seen anyone who looks like they need to lose weight there. I was at 27 and even stopped lifting weights to get it to 25 before I went plus that helped lower my blood pressure.
The SIM is pretty straight forward. Think of it as an ATP checkride. I didn't get multiple failures at once but I did get several failures on the interview ride. There is basically nothing different between the interview ride and the CAAC ride.
I still have all the study material for the ATP that I could find. Its not all in English but it will give you enough to pass on. PM me and ill share it. I couldn't upload it here cause its to big.
As far as talking to them before you have the type and time. It is worth a try. Depends on who you talk to and how much English he speaks.