Its no bother at all bro

I'll be glad to help! I will answer your queries as per my own opinion and insights now:
1. If you already have the NADRA Birth Certificate, then there is no need to get a new one. These NADRA certificates are issued for life, and are not required to be renewed. This issue is resolved
2. As per your information that you've provided, you have the proof-of-ties to home country quite solid. You can ask your father to get that appointment/employment letter signed, but if you can show the ownership of the institution as being your own, as well as the finances generated (bank slips etc), then you can proceed to the next step with ease.
You should show your bank statements as well as a good sum of funds required to sustain your MBA in Canada. From what I've learned, a well established person with a good funding can get visa better than one who lists a more humble investment. But that is only my own opinion.
Similarly, I saw a few refusals based on the course chosen as being declared as 'Monotonous or similar' to the course an applicant already had completed by the Visa Officer. As you're choosing another MBA course on top of your previous MBA, it might get problematic for you in your pursuit of a study permit. Again this is my own opinion based on my research/perceptions. So some more experienced member(s) might be able to answer these queries in full. Regards!