On a 320k property Ill be paying 9k annually. 

You'll want to get a tax estimate if you sold in 2024 so you can pay in the appropriate amount of tax (Assuming you didn't do a 1031 exchange).

You will pay for the higher risk with higher rates and origination fees but if the deal makes sense then congrats.

I will have to have money lined up somehow to pay him.

If you want the "best" rate, be prepared to pay for it.

One thing to think about are the tax implications of being a Canadian paying US taxes.

Do I have to pay for assigning a contract?

If this is correct, how much are you cash flowing each month after you pay your operating expenses and make your loan payment?

Sometimes they forget to tell you that many tenants in Detroit don't pay (depending on the property manager skill and the type of tenant) - but taxes are very high in the city and so is insurance. 

Note - if you live in your property for 2 years out of the last 5, then you don’t pay taxes on the profit.