Understand how does P05410 work.

Hello, 

I'm trying to understand how does P05410 work. When we hire a new employee, he/she has a possibility to add the date new hire, name, address line, telephones , etc in P05410. 

1) This program (P05410) is only for new hire employees? After that, where the employee can change their personal information?

2) Can we use this program for import personal information without to know job budgeting?

3) When data entry is completed, the Address Book and Employee Master (job tittle, Business Unit) are updating automatically with the personal information entered by the employee?

4) Where can I declare the HR email which the button "Send E-mail to HR" uses?