If she is prohibited because of this clause in the constitution, then taking a pay cut wouldn't make it OK. The emoluments will still have been increased. It would not be in her power to lower the salary to get around this prohibition.
No but it would be within the power of the same Senate which will have to approve her appointment to the cabinet.
I can't imagine why they would be willing to confirm her but not to revert the emoluments of the position.