Rental property loans are usually 0.375% higher interest rate than a non-owner occupied loan. Or the borrower can pay 1.5 more points and keep the same rate as owner occupied properties.
Lenders use 75% of rent, less principal, interest, taxes, insurance to determine cash flow and if the cash flow is negative, the negative cash flow is added to the borrower's other debts to see if borrower can qualify for a loan on the property.
Loan to Value Ratio:
Usually fixed rates loans are for 90% of value for purchase and no-cash-out refinance, and 80% LTV for cash-out refinance. For three or four unit properties the loan-to-value ratio is often lower, with even lower LTV's for cash-out refinances.