For both 1, 2 and 3: look at https://docs.q2developer.com/docs/guides/core_integration/index.html#multitenant-multi-core-extensions
For 4 and 5: instead of standing up online banking in your local environment you can connect to a sandbox environment that is running in AWS. To do so follow the guides here: https://docs.q2developer.com/docs/setup/index.html Once you are setup you can log in to your sandbox environment that is listed in your dashboard https://developer.q2.com/dashboard. This won't have a direct link to a core. Any of those calls you will have to work directly with the core provider and simply mock the solution in the sandbox before you will be able to end to end test in an FIs Staging Environment.