Basically, once you declare your rental income on your taxes of 2021 you will be able to prove that you are generating money from your property and the mortgage is being paid off.

This case wasn't a regular sell, The owner declared bankruptcy, and the tenant received wrong information from a friend.

By declaring 92% of the property as a rental, you can only roughly take 8% advantage of the Sec121 capital gains exclusion of $250k single and $500k married. 

If 2 properties are purchased (let’s say one in Ajax and the other in Toronto Ontario) does one have to officially declare one of them as being a primary residence?

While I am sure this is not your intention, to declare that you will be living in the property as your primary when you have no intention of doing so is mortgage fraud, which is a felony punishable by up to 5 years in prison. 

Send them the initialed page on the lease where it says tenant needs to provide annual declaration of insurance per the lease.

Spending some money with them now will save you some time and money, most likely.I am not sure about the laws where you are, but I know LA's eviction moratorium ties into a "self-declaration" of impact from covid19, financially.

When the company declared bankruptcy, they had bad debts from 3 customers that owed $50m each. 

I have a sideshave, dress dark and excentricly, am a publicly declared satanist trying to start a public church in my area, and working on some wicked tatts.

The city has declared the third, basement unit illegal and has given the seller notice.