In case you are moving to AEM forms JEE then everything that was in Livecycle will be available to you. In case you are moving to AEM forms on OSGi then the Livecycle workflow would not be useful and you will have to create AEM workflow.
Do Workbench process convert into AEM workflows? Yes, in case of AEM JEE workflows
Are PDF XFA forms used as Adaptive Form Templates? Yes, you can use XFA templates.
Can I use Adaptive forms with Workbench processes? Yes, off course.
What else do i need to transfer? LCA, Forms, custom components(if any) and data if you had long-lived processes.