(a) Subject to subsection (b) of this section, nothing in this chapter shall affect the authority of any management official of any agency—
(2) in accordance with applicable laws—
to assign work, to make determinations with respect to contracting out, and to determine the personnel by which agency operations shall be conducted;
(C) with respect to filling positions, to make selections for appointments from—
to take whatever actions may be necessary to carry out the agency mission during emergencies.
(b) Nothing in this section shall preclude any agency and any labor organization from negotiating—