Bancor is a protocol for creating erc20 smart tokens. Which allows users to trade through smart contracts.
Haven't heard anything about a DEX through Aion tbh. Is there an article or something you might have for reference?
No, It's not possible to create ERC20 tokens using Bancor platform this project is only providing liquidity option for these kind tokens and now it heading towards cross-chain transactions and trade on the same place with comfort. You should have to read the whitepaper.