Hello,
There is no simple answer for your question. There are alot of things to consider and you should contact a Cisco Account Team or Cisco Partner for different options regarding to you DMS needs.
That said.. I will address your question in the GENERAL sense...
You do NOT need a DMM to manage DMPs BUT with 20-40 Management, Configuration, & Scheduling tasks are made simpler and more efficient with a DMM.
ACNS is not required in a DMS solution. Depending on your Network Topology will determine your needs for Content Delivery systems. You state this is on a LAN not a WAN or Remote sites. Content can simply be stored on a Web Server(s) and the DMPs access URLs from there OR accessed via CIFS mounted drive.
As I mentioned before, please contact you local Cisco Rep for a more detailed assessment of your Needs..
Cheers!
T.