Reaction of aluminum hydroxide and nitric acid
Aluminum oxide could be the product of fusing Al(NO3)3 at high enough temperature. Aluminum metal would not be a product, in water or in fused salt.

2.Aluminum metal does not readily dissolve in nitric acid because of formation of passive oxide/hydroxide film. The nuclear power industry had need of large amounts of aluminum nitrate, and it was made by dissolving aluminum metal in hydrochloric acid (very fast) and treating the solution with nitric acid, boiling off the HCl. 


Aluminum metal is often prepared for welding by removing the oxide film with dilute hydrofluoric acid. The aluminum surface is bare metal for, oh, maybe a microsecond, before oxidizing back to the oxide. But the aluminum oxide film will be very thin for a few hours and easy to weld. The oxide film grows thicker in air as it ages.