I am a U. S. Federal Empoyee that is stationed overseas, and I receive a non-taxable housing allowance for the place I am renting while overseas. However, I have a home in Virginia that is unoccupied and due to the homeowner rules cannot be used as rental property. Under these circumstances may I depreciate the house? Deduct all of the expences used to keep the house in good repair (water, electric and gas, insurance, security alarm etc)?

Sorry, but unless the property is a rental property, you CANNOT deduct any of the maintenance/upkeep costs, nor can you depreciate it.