1. They don't. Clients ask an MP for a list of all DPs with a particular piece of content on it based upon the boundaries within a content location boundary group that the client falls within every time the client needs to download content. Thus clients
are never "assigned" to a DP in any way.
2. This is not accurate, as mentioned, the DP is determined dynamically and on-demand every time the client needs content. This is not explicitly tracked by ConfigMgr anywhere.
Jason | http://blog.configmgrftw.com