Mississauga (at least for sponsorship applications) do not send out any AOR. Once you submit your application to them, it's either you would get the whole package back (if it was lacking or something) or you would get a decision from them.
No, the AOR letter does not mean you have been granted the visa. All it means is that the government is confirming they have received your application. No decision has been made at that time. You are still at the very early stages of the application being processed when you receive AOR.
Here is what our AOR letter stated (and this is what you should expect to receive a few months after your application has made it to the visa office, provided that your application package was complete with all their requirements):
This is an automated message. Please DO NOT RESPOND to this message.
Dear [Sponsor Name],
This confirms that your application to Sponsor a Member of the Family Class has been received by Citizenship and Immigration Canada (CIC) on [YYYY/MM/DD] on behalf of the following member(s):
No, it does not. Its one of the first things you receive to let them know that the package is in their hands and considered "complete" as in it has all the necessary signatures and forms included in it. Nothing more.
I applied 4 months ago (inland) and haven't received any email/mail. Linked my account using my UCI and personal info and got an Application Number. That means that my application is complete and it won't be sent back?
Not sure what you mean by "should have" booked your flight by 13th October? You probably won't have a decision made for at least a few months, possibly even not for another year (or longer in some cases). It's extremely unlikely that your application would be fully processed by next week.
Until you receive your Confirmation of Permanent Residence document (COPR), you still have weeks to months to possibly years (in some cases) of waiting left.