You are allowed to claim only Mortgage Interest paid, not Principal. Add it on T776 in the interest line.
And is this deduction allowed if you are claiming the rental property as your principal residence even though you don't live there but still use it as your mailing address and rent it out 100%?
In my case for 2019, since it was my first time renting out my property, I rented out the whole property starting in June of 2019 up to and including December 31, 2019. I plan to write the required letter to the CRA that states I will continue to claim the property as my principal residence for that portion of 2019 (7 months) despite my renting it out.
I have also notice that I can also deduct condo fees, home insurance costs, and property taxes. Is this correct?
You can claim your now rental unit as your principal residence as long as you are eligible- As per CRA- https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/tax-return/completing-a-tax-return/personal-income/line-127-capital-gains/principal-residence-other-real-estate/changes-use/changing-your-principal-residence-a-rental-business-property.html
Rental expenses that you can claim - https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/rental-income/completing-form-t776-statement-real-estate-rentals/rental-expenses-you-deduct.html
How do I enter rental income and expenses in TurboTax