If I export and zip up an app using b4a and give that to a client, would there be anything else they might require to get the app compiled and functioning? ie. ( additional libraries, signed key?)
you mean you are giving them the project... the .b4a?
Then not only they will need all the libs referenced in the project, but the B4A itself, otherwise they wouldn't be able to open it in it's environment so no way to compile it.