Might do better on the Flight Testing thread; I would think the airbrake question is specific to the type, in this case Meteor.
I'm no Test Pilot ( cue for someone who is ) but I'd guess diving with airbrakes already deployed is generally OK - depending on the mechanical setup - but reaching warp 9 in a dive then expecting to deploy the brakes might be asking a bit much, and there's the risk of asymmetric opening or failure which would be a bad thing.