Queries on replication

I am a newbie here. I have follwoing queries:

  1. How does replication work in Couchbase?
  2. Can I have controlled replication? Suppose there are 4 nodes in a cluster and I want the document to be replicated to only one node ( sending node and receiving node). Is this possible?
  3. Can I use a proxy server in front of Couchbase server?