There is no charge to the creator, all the funds from the sales go to the creator.
Lastly, the mint fee doesn't apply to admin minted NFT (airdropping).
The best way to find the mint fee for a specific contract is to retrieve it from the contract by calling the mintFee function. You can read more about the mint fee here.
Mint Function
Purchase tokens given a minter contract and minter arguments
minter: The minter contract to use
tokenId: The token ID to purchase
quantity: The quantity of tokens to purchase
minterArguments: The arguments to pass to the minter (detail in the minters section)
*The minter arguments are different for each minter contract and are listed in the section.