For your first point, you will find that the PAP2 is functionally identical to the SPA-2000. That includes being able to use the Sipura User Guide (download from www.sipura.com/support) as a reference. You will learn in that document that "Enable IP Dialing" lets you pick up the attached phone and dial, for example, 12345*192*168*100*44*5060# to reach sip:12345@192.168.100.44:5060. Not very useful.

Rather than enabling this feature, you should seed your Dial Plan with elements that translate dial codes into desired URIs. You can find examples of how to do this in the "How do I craft a dial plan?" sticky at the top of this forum.

The User Guide will also tell you that there is a method of coding username and password into a Dial Plan element, but only for the SPA-3000 (and, even so, it's reported to not be very reliable).