2) They do have 32GB SATADOMs, but these are intended for boot media and configuration only. They are not intended for anything more than boot media. Think something like an SD Card in a solid-state machine.
3) Yes, I want this. No, we don't do it currently.
FWIW, we didn't build all this. Ironic existed long before we came around, we added a deploy driver and set it all up and exposed it for customers. We'll have a blog up shortly with exactly how we're running this in production.
The coolest part of all this is something nobody has mentioned here yet -- this is all on Open Compute hardware. When I managed servers, I always wanted access to the cool hardware and scale that companies like Facebook and Google had. Hopefully with OnMetal, we're going to give our customers the cool hardware I always wanted.
Edit: As a note, I'm a Racker and I work on the team that built this.