Integration between LN CE and 3rd party cloud-hosted web application

1) To publish Sync BODs as JSON Files, my 'Data flow' need to call the API of 3rd party application. Which type of connection point need created? Image of List attached.
2) The 3rd party application will call LN BDE. So, there will be no Data Flow as I dont have to transform. What would be the 'Type' of 'Authorized App' registration? Backend or Web?
3) Is it necessary to register 3rd party API suite under 'Available APIs' or it is just possible to call needed endpoint URLs they provide to publish Sync JSON files?

basic questions, I guess. Many thanks