Yes but the owner must execute the edit tx so you will probably never be able to edit all Nfts except if there is very small quantity. Maybe you can see with Tradeport if they can map old_attributes to new_attributes

Yes, it's possible if the NFT's smart contract includes functions for updating those attributes. For marketplaces like TradePort, you'd typically update the associated display object, which signals them to re-index the metadata on-chain changes.