Will I qualify for the FHA loans?
That is the best use of a family member to co-sign for you, a debt ratio that's too high. Go for it. And you will be eligible for the entire $8,000 if the selling price of the house you are buying is high enough. The interest rate you will get isn't any higher either because of needing a co-signer. If...

How much equity is needed for reverse mortgage?
The equity position depends on the age of the youngest borrower. If you are in Florida please give me a call and we can discuss it.Charlie