Where are the Ordinariates / Rome at in finalizing a common Anglican missal for all three Ordinariates?
It was completed last year.
Is it being used across the board in all three Ordinariates now?
Yes it is, or at least, should.
Once other material is completed (e.g. Divine Office) it will probably be released as a “Book of Common Prayer”-style publication. Right now, the Ordinariate parishes just use a loose-leaf binder of officially-published sheets for the Missal.