Estimates. If the customer accepts the estimate in PrintJobManager, does it transform into a Job?

Yes, PrintJobManager automatically creates a job when a customer accepts the estimate.
 
The customer will also be automatically sent an Order Acknowledgment email. The default Order Acknowledgment email will use your company name. The default email subject line and body text can be edited by you.  For example, some change the text to read as an invoice payment request with instructions.