A: It’s extremely unlikely that the situation would occur that zero Queens have been eliminated in the game by the time you are eligible to create one via Field Promotion, but if it happens, yes, it is allowable. If you meet the criteria of having no Queens in your own territory, you may create one via Field Promotion, even if this means there are more Queens in the game than it started with.

If you don’t have any additional Queens in your collection to substitute in for the Pawn-Drone combo on the board, just move the two stacked pieces as though they were a Queen.

(It’s kind of like your Pawn climbs onto the shoulders of your Drone, and they put on a single trenchcoat, and they’re functionally indistinguishable from any other Queen on the board – which implies by extension that three Pawns in a trenchcoat could also be a Queen…)