Dogs have very sensitive hearing and can hear things that us humans cannot hear.
Sometimes dogs will bark at even the smallest things they hear such as a leaf or if they see a leaf fly by outside.
So it may be that the dog sees or hears something that you do not and that could be why they are barking at those things.
Small Dog Breeds such as the Pug, Poodle, Chihuahua etc are some of the longest living dog breeds.
I've heard of a large dog that lived 20 years but that is rare.
Most large dog breeds live only 8 to 12 years while small dog breeds typically live for 15 to 20 years depending on the breed of dog.
Small dog breeds will live the longest life compared to larger dog breeds.
With small dog breeds they typically live from 15 to 20 years while larger dog breeds might only live as long as 8 to 12 years.
So if you want to have a longer living dog breed then you should go for the small dog breed such as the little Toy Poodle or Chihuahua who can live from 16 to 20 years and sometimes a bit longer.
The large dog breed Australian Shepherd is one of the large dog breeds that has a 15 to 16 year lifespan which is a pretty good lifespan for the larger dogs.
A yellow lab dog lives from 12 to 14 years on average so that makes them a pretty long lived dog.