The Lightning address used is just what is set on your Nostr profile; when you receive payment (via NIP-17 DMs under "orders") you should be able to instantly redeem the sats to your profile's Lightning address without having to mess with any of the Cashu settings by just clicking "redeem."
As for eNuts, if I'm not mistaken, it is actually no longer maintained, so coinos might be a better wallet to play around with if on iOS. You should still be able to generate a new token by selecting "send" or "send ecash" and copying the token that is generated, though.