In a typical rent to own agreement, you usually pay a bit more rent than on a regular rental. In same agreement, you have the option to buy the house after 1, 2 or 3 years, depending on the contract you sign, and a very small amount of the rent would be applied to down payment. But, you'll have a problem if by then, you still cannot get a loan.
My suggestion is to forget a rent-to-own for now, get yourself a nice rental place, close to work, and at a price you are comfortable with. In a rental property, you have no expenses like fixing appliances if they break, no property taxes, no insurance, etc.. Forget about owing a house for now, and concentrate on getting ahead, get out of debt, fix your credit, and save some money. Do not get yourself deeper in trouble.
Home prices are now getting to a reasonable price level again, and they'll stay at this level for a few years. We do not expect home prices to be more than 5 to 8% higher in the next 5 to 6 years. By then you should be in a much better position, and can buy a house without feeling that you are running uphill all the time.
And, by the way, NO you cannot use the lessor's deposit as down payment for another house you are renting. That money should be in a separate bank account. It is not your money, it is the lessor's money, in your trust.