1. It can be a different tag, specific for NIP-94.
2. This new tag specific for NIP-94 can reference URLs that are inside .content verbatim or in other special ways, since it is custom.
3. No, if the events are not "special" and you're only interested in having most clients display their .content and .author, then you don't need special treatment. But if you want clients to do special things with them that need special code to be written, then what is the issue with adding a new special tag?