Did you add a field group (payload) in your data source or just save it as blank with a name and url? Please make sure required field-group payload is also added, it should be instantaneous.

In test mode you can. If the journey is live you will need to look at the reports to see the errors occurring. This will give you a count of errors but not the specific response from your service. For those, you will need test mode or to look at the logs for your service.

Start with this tutorial - https://www.adobe.io/apis/experienceplatform/home/data-ingestion/data-ingestion-services.html#!api-specification/markdown/narrative/technical_overview/streaming_ingest/getting_started_with_platform_streaming_ingestion.mdCreate a profile schema that has testProfile in it. Then update that profile using postman to mark your ECID as testProfile = true

Yes. We are planning to release this functionality in Q2 of 2020. This will allow customers to view step information from a Journey out of an individual dataset.

Yes! You can use Adobe Analytics data in Adobe Experience Platform. This requires the Analytics Data Connector to be activated and this automatically lands all Analytics data for a report suite into a dataset. You can activate this dataset for Unified Profile and thus make it available for use in Journey Orchestration. These fields will need to be added to the ‘ExperiencePlatformDataSource’ as part of a datapack.