Converting primary residence into rental (mortgage is paid off): Can I take depreciation on this converted property for taxes?

I just paid off mortgage on my primary residence and I am thinking of buying a bigger home (as a primary residence) while renting the existing home.  Can I depreciate current home (since it's going to be considered as a rental property) on my taxes or is it just available when you have mortgage on it?  Also if I take HELOC from the current house to pay down 20% on new house, can I take mortgage interest deduction on taxes?