It would be worth consulting with the Primal & Damus devs to find out how they navigated these questions. I suspect the “correct “ answers are:

- No. Zapping is a gift, not a transaction.

- No. All users of the NOSTR protocol have keys, which are their identity on the decentralized NOSTR network. The user’s app preferences are tied to their identity (keys), including blocking and flagging, within the app. Abusive users may find their keys blocked not only within the app, but also by NOSTR relays, disrupting their access to NOSTR apps across the ecosystem of services on the network.

- The purpose of integrating NOSTR keys is to include NOSTR users, who are identified by their keys.