If I use the document service sdk to combine pdf's, will the documents be uploaded to the cloud?
Yes. However, any storage is transient, short-term, and for processing only. Any content utilized by the APIs that needs to be stored on the Adobe cloud will be there for no more than 24 hours. Plus, once the API “transaction” is complete, the pointer to the content is lost and cannot be recovered – so once all API calls for that particular process are over, there is no way to get to that stored document again.