Some of those items raise a few questions, like how to setup a FIM service that only takes requests from the sync service? Do we setup multiple FIM Service instances and then configure the FIM MA to talk to one of them, and not make that one available to web clients?
So the short answer to my last question is yes and then Darryl answers the first question in great deal.
Here is his answer: Service Partitions - Multiple Middle Tiers, Request & Workflow Processing
Great job Darryl! I see this as a great way to ensure good response time for users and to scale out.