: What are the components of a mortgage, is it only interest, principal, tax and insurance?

Ensure the principal or deal sponsor has a strong resume.

Since you didn't finance the purchase of the house itself, it is likely that the partner will offer to pay you principal + interest rather than a share of the profit (at least that's what I would do).

In this scenario:  1) I would borrow somewhere between $1,000 and $4,000; 2) Lender would get all of the monthly payments until they were paid back in full (principal and interest); and 3) repayment in full would take between six months and two years.Of course, such loans would be secured by the property.  

I've helped 3 couples  in the past 3 months house hack duplexes since they're friends of family and extremely happy with their purchases as their total outlay is between $0-$400/month so when you include principal pay down, they are living for free. 

If you intend to pay off the loan sooner then the commercial is the loan to choose as you will be pushed to pay more principal down faster.  

Here are a few numbers on the house:Purchase Price: $301,000Remaining Loan Balance:  $285,000Improvements: $30,000Improved Home Value: $340,000Rental Income: ~$2,700/month for both unitsP&I: $1390/month ($450 principal, $940 interest)Taxes: $340/monthInsurance: $310/monthRepairs and Maintenance: $135/monthCapEx:  $135/monthPMI: $205/monthProjected Appreciation: 1-2% per yearYou'll notice I have not included the cost of a property manager in the numbers above as this would put me in the red every month.  

Still, the main question is whether or not $500 per month to principal + $200 per month rent with low/no cash flow is better than the refi for cash and the lower payment option? 

We are currently in the market as a brokerage and also buying investments as Principals.

Then we add Depreciation and principal pay off part of mortgage.