There are many domestic & international flights to Da Nang by VietnamAirlines, VietjetAir or Jetstar... It's a good idea to check airfares often because prices fluctuate all the time.
From Da Nang International Airport or city center: you can either take a taxi to Lady Buddha Da Nang (14km), the fare is around 200.000-250.000VND or rent a scooter and drive by yourself (rental fee ~150.000VND/day).