Nope. You’d have to break the unions first. Do that, and a LOT of problems (including some deficit issues) go away over night.
That should be a goal in his second term
Ditto that.
FedGov unions were allowed in by a JFK Executive Order, likewise a Trump Executive Order could decertify them and they would be gone. (Even FDR thought government unions were a bad idea!) You would then need legislation to keep another EO from bringing them back.
At the state, county & local level it will be much harder to get rid of them because usually legislation\ordinances allow them. Still it could be done if the will is there to do it.
Nope. They can be fired for bad conduct. 30 days notice is required.