Scaling with Proxy Nodes

I have a few questions about setting up the proxy nodes as described here: Scaling with Proxy Nodes

Is this a Pro Feature?

How do I best implement this? I already have a Nexus that has an internal maven repo as well as a public proxy repo and combines them in a group. What do I then set up on the proxy node? the same group name and below it 1 proxy that points to the main node?

Is there a way to simply use all requests that come to this proxy node as a proxy? or do I have to set this up for each repo that exists on the master node?