Update documents Sync Gateway (II)

I’m trying to update documents:
Android Device (REST API(Http PUT Request)) --> Sync Gateway --> Couchbase Server 2.0,

as it says:

I’m interested in making doc updates directly through Sync Gateway (without CBLite replication).

I have several questions about this:

  • 1) Is it possible to update docs the same way that CAS and APPEND do? (by REST API or other way directly through Sync Gateway, without CBLite replication)
  • 2) If (1) is not possible, How I can do to add new "fields" to a document without re-send the entire document again to Sync Gateway?
  • 3) Can the sync_function add and make changes in the "fields" of JSON that arrives before storing in Couchbase Server? Does .getDate() work in sync_function?