The check digits enable the sending bank (or its customer) to perform a sanity check of the routing destination and account number from a single string of data at the time of data entry.
Generally, interest rates on FHA-backed mortgages are competitive with conventional mortgages. A quick scan of interest rates for 2012 reveals that FHA mortgages feature rates of about 3.33 percent. The FHA states that the average interest rate for a 30-year fixed loan on a single-family home is about 4.06 percent.
Interest rates on FHA-insured mortgages are subject to negotiation between lenders and borrowers like any other mortgage. What your interest rate might be with an FHA-insured mortgage depends on several factors, with credit history being only one of the factors.