I just created a Vault account on my Coinbase account. When the money is deposited into the Vault does it stop growing or will it continue to grow based on the coin?
The amount of cryptocurrency you deposited into the 'Coinbase Vault' will remain the same (unless there are some fees levied by Coinbase for the storage, etc). So if you put 1 bitcoin in, later you will be able to withdraw 1 bitcoin. The value of that 1 bitcoin (measured in USD) may change during that time, but you will still own the same amount (1 bitcoin).