One of the way to automatically publish new content added to DAM would be modify dam workflow on author to include custom process step to activate the asset.
For version purging refer  and also make sure the workflow in publish is disabled.
Create a luncher in workflow console and select the following properties
Eventype : created
NodeType : dam:Assest
Path : /content/myweb/dam
Workflow : Publish Example
Activate : Enable
Exclude List : optional
Runmode : Author
luncher will automatically publish the newly added dam assests. I Hope it will help you