How can one achieve incredible chakra such as that of the Third Raikage or Kisame? Kisame was known as tailed beast without tails. This is because he had an incredible amount of chakra, so much that Samehada had an affection toward him.

A's father, the Third Raikage, could even combat the Hachibi all alone!
What is the source of such an amount of chakra? Is it hereditary? Or won by practice? Or just by birth?

Might Guy, the Green Beast of Konoha, opened the 8 Gates to surpass Kisame, but doing this takes a risk on his life. So it is certainly not the manipulation of chakra points, since neither the Third Raikage nor Kisame seem to be risking their lives to get such an amount of chakra.
There are times where a genius is born. It doesn't have to be in raw chakra, but in skill, brains, willpower, etc. 

Itachi for example is considered a genius, a fast learner, combat analyst and very powerful.
Madara is a genius. Awakening the Mangekyo, having power many shinobi feared.
A's father can also be considered a genius. Steel skin and iron blood, along with the incredible chakra and durability to match that of the Eight Tails. 

Kisame is a slightly different case. He's definitely fearsome strong, but his gigantic chakra reservoirs actually came from his sword, Samehade, which has the ability to consume the chakra of the victims it hits.