Insurance would cover it, I would pay the deductible, and no assets would be lost.If you are in an area like San Diego where people are more likely to sue, a judge is more likely to find you guilty, and the payout is expected to be higher, you may consider an umbrella insurance policy.

However while people in Windsor doesn't have the luxury of high paying jobs that GTA residents have, is it just a temporary fever of buying houses, or there is really something going on in this city ? 

Make sure the tenants are paying market rent or above, otherwise your loan will be DSCR constrained.

Example: If a business buys an oven and it costs $5,000, and $1,000 for installation and setup, and $200 of delivery and transport fee. 

I ran some of your numbers, assumed rent of $1,290/unit and that you pay cash for the rehab costs.

They just pay the invoices.

For a 30 year Conventional loan, I'm at 6.5% rate (6.808% APR) for a duplex, 95% LTV, 780+ FICO, owner occupant.And I'm assuming they're paying $2k of your closing costs - not your down payment.

And you don’t have to pay it back when you sell, you do an exchange.

I don't know the rules in the US, but in Canada, you can do that every 2 years and when you sell, you don't pay taxes on the capital gains.

Suggesting to them buying their house for a wholesale range offer or lower dependent on the extent of the rehab, then having a contract in place that gives them a percentage of the profit to help get them back on their feet, paying off debts etc.