Any tools to check what would be the approximate gas for a transaction for a certain contract for different blockchains?

check estimate gas in Web3.

hey, how can I check that?

https://web3js.readthedocs.io/en/v1.2.11/web3-eth-contract.html#methods-mymethod-estimategas

Is it possible to check current contract's owner? Also, could contract has more than one owner? Speaking in terms of the onlyOwner annotatiin