Yes, they are away of due date because when you go for medicals, the doctor will examine your wife to know if she is pregnant and once dey confirm, they will ask for her due date and month based on her last scan and this is captured in the report sent to cic by the medical examiner..
So once the VO reviews ur application, they already know your are expecting a baby based on the medical report...In our own case, they sent us a letter and told us to submit all baby's doc(birth cert, international pp, medical report) and processing fee for baby once baby is born. and we should also submit a new additional family info form to include baby's details as well with our pp.
Yes it would take one year cus av seen some1 in same situation...however it also depends on VO.
Yes they will think that because you did not include the dependant in the initial form.
Get in touch with your VO.