not sure if they're necessary since Gatcoin controls everything about any tokens minted for their customers.
Exactly, there's no need for smart contracts, they just need to mint tokens based on merchant's demands. I don't see merchants manage directly all their tokens
The purpose of smart contracts in GATCOIN will mainly be to help merchants control the use and expiration of their Merchant Tokens. So if they want to issue a promotion for a certain period of time before the Tokens expire, this will be done through the smart contracts. Another reason why we think this is such a great solution!
Smart contracts on the new chain? How they will be compiled? Solidity? Viper? A new program language like Plutus (when Cardano team will deploy it) maybe?