Estimates. Can a price estimate in PrintJobManager (APJM) give a “best price” when there are both digital and conventional print processes available?

Yes, provided you create the Product pricing with that in mind. For example, for quantities below 10,000 specify the digital workflow, while quantities above use the conventional workflow. The estimate price for quantities below 10,000 will be based automatically on digital, while quantities above will be based on conventional workflow.