When nodes are added, they should automatically appear in PDC 'soon' (two to five minutes). You may need to log off to get drop-down lists to refresh.
When nodes are removed or go out of service, they stay in PDC drop down lists for 30 days. There is a nightly cleanup process in PDC that checks each node record and looks for alerts, exceptions, health status and usage data associated with that node. We keep alerts and exception details for two weeks; usage data and health stats for a month. If there is no data associated to a node, we delete the node record.
PDC portal does not support branding and skinning at this time.
There is no concept of application-specific subscriptions in PDC at this time. Please elaborate on your use case and provide some examples so we can consider that as a future feature enhancement.