HCM Processes and Forms Fundamentals

Hi,

few questions:

a) How is HCM different from HR-ABAP

b) Pre-requisites to understand HCM as I am from Workflow background.

c) Workflow scenarios in HCM (appreciate a link)

d) SAP training course for HCM

e) SAP Best Practice on HCM.

any anwer to the above is appreciative.

Thanks.

Aditya