International Collaborations -- Legalities, agents, etc.

If one were to do a collaboration with a writer in another country, how badly would that complicate legalities, getting an agent, etc? Would we get one agent in one country? Or submit to publishers without an agent? Etc.

Neither of us is currently published, neither has an agent. We're just brainstorming about a collaboration, and are wondering just what we might be getting into with the international stuff.

Ideas? Thoughts? Experience?