Could I use the income from a rental property to quialify for a refinance?
Yes, it's possible depending on your situation.
Yes. Most lenders will count a percentage of the income from the property toward your debt to income ratio. The percentage will vary between lenders as will the time you must own and operate the property before they will consider the rental income.
Many lenders also require that you show rental income on two years tax returns in order to include the rental income for loan qualification.