Hardware Configuration Questions

I have a Panasonic KX-TG-4500 small office phone system with 8 wireless extensions, a Polywell Soundstation II, a fax (outgoing only, incoming uses eFax), and a security system (analog dial-out) currently jury rigged thru a two line Vonage adapter. My understanding is that replacing it with an Asterix based system would require:

A. Two (2) POTS adapters
B. A two (2) or more line VOIP service account
C. A VOIP fax account thru Digium

Is my understanding correct?

I don’t seem to understand the difference between the ADM and TDP class of telephony interface cards? and then within that choice I believe I need station interfaces vice trunk interfaces, correct?